ytdl_hook: can't play videos from Steam store page (no unique URLs)

mpv Information

mpv v0.40.0-287-g194ce88ac Copyright © 2000-2025 mpv/MPlayer/mplayer2 projects
libplacebo version: v7.351.0
FFmpeg version: 7.1.1
FFmpeg library versions:
   libavcodec      61.19.101
   libavdevice     61.3.100
   libavfilter     10.4.100
   libavformat     61.7.100
   libavutil       59.39.100
   libswresample   5.3.100
   libswscale      8.3.100

Other Information

- Linux version: Gentoo
- Kernel Version: 6.12.42
- GPU Model: Advanced Micro Devices, Inc. [AMD/ATI] [1002:7550]
- Mesa/GPU Driver Version: Mesa 25.3.0-devel (git-cc0dc4b566)
- Window Manager and Version: https://github.com/conformal/spectrwm/commit/5dcffa21804f9cebc857d2a6931c2bd6f7380139
- yt-dlp version: https://github.com/yt-dlp/yt-dlp/commit/526410b4af9c1ca73aa3503cdaf4d32e42308fd6
- Source of mpv: Official Gentoo ebuild.
- Latest known working version: N/A
- Issue started after the following happened: 

After yt-dlp fixed steam urls (https://github.com/yt-dlp/yt-dlp/pull/14008)
I noticed some steam pages cause lau to crash.
Using yt-dlp to download the videos without mpv does work.

Reproduction Steps

\mpv --no-config --log-file=/tmp/output.txt https://store.steampowered.com/app/2581410/Stygian_Outer_Gods/

Expected Behavior

It should play the 5 videos on the page.

Actual Behavior

[ytdl_hook] 
[ytdl_hook] stack traceback:
[ytdl_hook] 	@ytdl_hook.lua:1191: in function 'on_load_hook'
[ytdl_hook] 	@ytdl_hook.lua:1195: in function 'fn'
[ytdl_hook] 	mp.defaults:609: in function 'handler'
[ytdl_hook] 	mp.defaults:522: in function 'call_event_handlers'
[ytdl_hook] 	mp.defaults:564: in function 'dispatch_events'
[ytdl_hook] 	mp.defaults:515: in function <mp.defaults:514>
[ytdl_hook] 	[C]: at 0x558419f8a430
[ytdl_hook] 	[C]: at 0x558419f88850
[ytdl_hook] Lua error: @ytdl_hook.lua:1143: attempt to index local 'site' (a nil value)
client removed during hook handling
Failed to recognize file format.
Exiting... (Errors when loading file)

Log File

output.txt

Sample Files

Two example links:

https://store.steampowered.com/app/2581410/Stygian_Outer_Gods/
https://store.steampowered.com/app/2108180/Swordhaven_Iron_Conspiracy/

I carefully read all instruction and confirm that I did the following:

• I tested with the latest mpv version to validate that the issue is not already fixed.
• I provided all required information including system and mpv version.
• I produced the log file with the exact same set of files, parameters, and conditions used in "Reproduction Steps", with the addition of --log-file=output.txt.
• I produced the log file while the behaviors described in "Actual Behavior" were actively observed.
• I attached the full, untruncated log file.
• I attached the backtrace in the case of a crash.

Reproduce the failure with the two Steam store URLs and the provided mpv command, then inspect ytdl_hook.lua around lines 1143, 1191, and 1195 using output.txt for context. The fix is complete when these pages no longer trigger the nil-site Lua error and all five videos can be played.