dsh-mp4

Play MP4 / M4V / MOV videos inside the DeepSeek Harness right sidebar — the browser's own video player replaces the "this file type cannot be previewed" placeholder.

Why this exists

When the pane says "this file type cannot be previewed / download to view", the file is fine. No renderer claims mp4, and which preview system opens a file depends on what you have installed:

Your right column	What opens the file	Before
dsh-better-sidebar installed	its editor tab, picking a viewer through matchFileViewer(path)	ships markdown / html / jsonl / code only, so mp4 falls through to the catch-all code viewer, reads as binary → "cannot be previewed" plus a download link
Native DSH sidebar	@deepseek-ai/dsh-client-ui-sidebar-documentpreview	mp4 sits in UNVIEWABLE_BINARY_EXTENSIONS, matches no renderer → empty state, and not a single byte is read

This plugin registers with both, so one package works on Desktop, plain dsh web, and any other profile. The two halves are independent: whichever system is missing simply stays idle instead of failing the plugin.

Install

Search dsh-mp4 in the plugin market, or:

# Desktop users: prefer Settings → Plugins (Desktop runs its own profile)
dsh plugin --profile web add dsh-mp4
dsh plugin --profile <your-profile> add dsh-mp4