Changing youtube aspect ratio as a viewer.

[villadelfia]

I like to watch videos/games as they're supposed to be watched, so not squished or stretched. Unfortunately a lot of people on youtube apparently don't have eyes and upload their videos wrong.

They can even fix them by adding some tags, but they don't, even if you ask them to.

My question is, is it possible for me, as a user, to fix the youtube aspect ratio of videos without downloading them?

I have a few workarounds, but each has its own problems:

1. VLC: It can stream youtube and change the aspect ratio. Unfortunately it doesn't work for playlists, which I use quite often.
2. Laptop on tv: I can just letterbox the display on my tv, but of course I don't always watch youtube videos on my tv.

So now I'm looking for a solution that allows me to change the aspect ratio on youtube videos on my pc, which either works in the browser or is a standalone program that supports playlists.

Does one exist?

EDIT: Literally minutes after posting this, I found a solution: http://userscripts.org/scripts/show/123503

That is a greasemonkey userscript which adds buttons to switch modes.

EDIT2: I edited the script a bit to add a function to fix windowboxed videos. http://pastebin.com/7hprRjxF