Record a video of the install process on all platforms

To graphically show how to use the installer, I think a video is the most effective way, rather than our current list of instructions. Having a recording for each platform would also be useful for explaining on Linux/MacOS as most of us are not familiar with those platforms/don't have a PC on those platforms.

This is also useful when debugging, since users can say "this part at 1:00 in the video doesn't happen", rather just explain that "nothing happens".

I actually recorded a video already just for the "partial manual install" because that is difficult to explain otherwise: https://www.youtube.com/watch?v=Px4JWsSycQE (this video is linked inside the installer)

I wouldn't be too worried about needing to update the video if something changes, since the basic install process hasn't changed in a very long time.

- [ ] Windows Video
- [ ] MacOS Video
- [ ] Linux Video
- [ ] Steam Deck Video
- [ ] This is a big pain point, because many Steam Deck users have a Windows background and are unfamiliar with using the Konsole + Steam Deck's desktop mode + proton/native etc. A video going through what we already have on the wiki would be very useful.
- [ ] This could be done without a steam deck by installing SteamOS on a PC, see [steampowered.com - Build your own Steam Machine](https://store.steampowered.com/steamos/buildyourown)

The issue asks for video recordings of the install process on Windows, macOS, Linux, and Steam Deck. Start by reviewing the existing wiki instructions and the linked partial manual install video. Use screen recording software to capture the steps, ensuring you follow the current installer workflow. The videos should be uploaded to a platform like YouTube and linked in the project documentation.

Written by the indexing model from the issue text.