How to write a program to speed up youtube playback

I want to watch videos from YouTube at a faster playback rate. A while back I asked if there is a utility that can speed up video playback. The only thing that was mentioned was some closed source project for Windows. I'm not a fan of either Windows or closed source.

Another answer mentioned that you can download videos from YouTube and play them back. Unfortunately, this no longer seems to work. I tried several Firefox addons and they all fail to download. So, now I think I need to build something myself. I see two options:

1. Create an addon to Firefox that allows me to change the playback speed of the video as it is playing.
2. Find an open source code alternative to Adobe's flash player and update the source code to have a variable rate of playback of sound and video.

I'm not sure if either option can give me the control that I want. I don开发者_StackOverflow't have a lot of experience with flash and was hoping someone more experienced could give advice on where to start.

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I think you won't really find a standard only-flash solution. Though I've seen something like this for mp3, written in flash, for changing the speed. It worked pretty well, but I think this can't be done with a NetStream object - the one used for streaming videos.

It doesn't have such properties, like speed or fastforward. The only way to change the playback is using the seek method, but I think it would give a terrible result - if it would work at all.

So from a flash point of view, it doesn't look like to be realistic.