diff --git a/.config/docker_example.yml b/.config/docker_example.yml
index c6c83a98bf..6d82fdcc79 100644
--- a/.config/docker_example.yml
+++ b/.config/docker_example.yml
@@ -106,7 +106,7 @@ redis:
 #   ┌───────────────────────────┐
 #───┘ MeiliSearch configuration └─────────────────────────────
 
-# You can set scope to local (default value) or global 
+# You can set scope to local (default value) or global
 # (include notes from remote).
 
 #meilisearch:
@@ -198,13 +198,18 @@ proxyRemoteFiles: true
 #   https://example.com/thumbnail.webp?thumbnail=1&url=https%3A%2F%2Fstorage.example.com%2Fpath%2Fto%2Fvideo.mp4
 #videoThumbnailGenerator: https://example.com
 
+# Enables the built-in thumbnail generator for remote videos. (default: false)
+# Only useful if "Cache remote files" is disabled, and "videoThumbnailGenerator" is unset.
+# Without it, remote video files that are not cached will not have any thumbnails.
+#enableBuiltinVideoThumbnailGenerator: false
+
 # Sign to ActivityPub GET request (default: true)
 signToActivityPubGet: true
 # check that inbound ActivityPub GET requests are signed ("authorized fetch")
 checkActivityPubGetSignature: false
 
 # For security reasons, uploading attachments from the intranet is prohibited,
-# but exceptions can be made from the following settings. Default value is "undefined". 
+# but exceptions can be made from the following settings. Default value is "undefined".
 # Read changelog to learn more (Improvements of 12.90.0 (2021/09/04)).
 #allowedPrivateNetworks: [
 #  '127.0.0.1/32'
diff --git a/.config/example.yml b/.config/example.yml
index 4aa7757c61..183331ef63 100644
--- a/.config/example.yml
+++ b/.config/example.yml
@@ -118,7 +118,7 @@ redis:
 #   ┌───────────────────────────┐
 #───┘ MeiliSearch configuration └─────────────────────────────
 
-# You can set scope to local (default value) or global 
+# You can set scope to local (default value) or global
 # (include notes from remote).
 
 #meilisearch:
@@ -213,13 +213,18 @@ proxyRemoteFiles: true
 #   https://example.com/thumbnail.webp?thumbnail=1&url=https%3A%2F%2Fstorage.example.com%2Fpath%2Fto%2Fvideo.mp4
 #videoThumbnailGenerator: https://example.com
 
+# Enables the built-in thumbnail generator for remote videos. (default: false)
+# Only useful if "Cache remote files" is disabled, and "videoThumbnailGenerator" is unset.
+# Without it, remote video files that are not cached will not have any thumbnails.
+#enableBuiltinVideoThumbnailGenerator: false
+
 # Sign to ActivityPub GET request (default: true)
 signToActivityPubGet: true
 # check that inbound ActivityPub GET requests are signed ("authorized fetch")
 checkActivityPubGetSignature: false
 
 # For security reasons, uploading attachments from the intranet is prohibited,
-# but exceptions can be made from the following settings. Default value is "undefined". 
+# but exceptions can be made from the following settings. Default value is "undefined".
 # Read changelog to learn more (Improvements of 12.90.0 (2021/09/04)).
 #allowedPrivateNetworks: [
 #  '127.0.0.1/32'
diff --git a/packages/backend/src/config.ts b/packages/backend/src/config.ts
index a550fdc364..137506bb64 100644
--- a/packages/backend/src/config.ts
+++ b/packages/backend/src/config.ts
@@ -86,6 +86,7 @@ type Source = {
 	mediaProxy?: string;
 	proxyRemoteFiles?: boolean;
 	videoThumbnailGenerator?: string;
+	enableBuiltinVideoThumbnailGenerator?: boolean;
 
 	customMOTD?: string[];
 
@@ -167,6 +168,7 @@ export type Config = {
 	mediaProxy: string;
 	externalMediaProxyEnabled: boolean;
 	videoThumbnailGenerator: string | null;
+	enableBuiltinVideoThumbnailGenerator: boolean;
 	redis: RedisOptions & RedisOptionsSource;
 	redisForPubsub: RedisOptions & RedisOptionsSource;
 	redisForJobQueue: RedisOptions & RedisOptionsSource;
@@ -272,6 +274,7 @@ export function loadConfig(): Config {
 		videoThumbnailGenerator: config.videoThumbnailGenerator ?
 			config.videoThumbnailGenerator.endsWith('/') ? config.videoThumbnailGenerator.substring(0, config.videoThumbnailGenerator.length - 1) : config.videoThumbnailGenerator
 			: null,
+		enableBuiltinVideoThumbnailGenerator: config.enableBuiltinVideoThumbnailGenerator ?? false,
 		userAgent: `Misskey/${version} (${config.url})`,
 		clientEntry: clientManifest['src/_boot_.ts'],
 		clientManifestExists: clientManifestExists,
diff --git a/packages/backend/src/core/VideoProcessingService.ts b/packages/backend/src/core/VideoProcessingService.ts
index e157160b45..c9f706e5c8 100644
--- a/packages/backend/src/core/VideoProcessingService.ts
+++ b/packages/backend/src/core/VideoProcessingService.ts
@@ -51,12 +51,14 @@ export class VideoProcessingService {
 	@bindThis
 	public getExternalVideoThumbnailUrl(url: string): string | null {
 		if (this.config.videoThumbnailGenerator == null) {
-			return appendQuery(
-				`${this.config.url}/proxy/thumbnail.webp`,
-				query({
-					url,
-				}),
-			);
+			if (this.config.enableBuiltinVideoThumbnailGenerator) {
+				return appendQuery(
+					`${this.config.url}/proxy/thumbnail.webp`,
+					query({ url }),
+				);
+			}
+
+			return null;
 		}
 
 		return appendQuery(
diff --git a/packages/backend/src/server/FileServerService.ts b/packages/backend/src/server/FileServerService.ts
index 6659932ed1..3614ea21b6 100644
--- a/packages/backend/src/server/FileServerService.ts
+++ b/packages/backend/src/server/FileServerService.ts
@@ -83,12 +83,14 @@ export class FileServerService {
 				.catch(err => this.errorHandler(request, reply, err));
 		});
 
-		fastify.get<{
-			Querystring: { url: string; };
-		}>('/proxy/thumbnail.webp', async (request, reply) => {
-			return await this.videoThumbnailHandler(request, reply)
-				.catch(err => this.errorHandler(request, reply, err));
-		});
+		if (this.config.enableBuiltinVideoThumbnailGenerator) {
+			fastify.get<{
+				Querystring: { url: string; };
+			}>('/proxy/thumbnail.webp', async (request, reply) => {
+				return await this.videoThumbnailHandler(request, reply)
+					.catch(err => this.errorHandler(request, reply, err));
+			});
+		}
 
 		fastify.get<{
 			Params: { url: string; };
@@ -395,7 +397,7 @@ export class FileServerService {
 		if (file === '404') {
 			reply.code(404);
 			reply.header('Cache-Control', 'max-age=86400');
-			return reply.sendFile('/dummy.png', assets); // TODO: return webp
+			return reply.sendFile('/dummy.png', assets);
 		}
 
 		if (file === '204') {