Here is a wonderful Firefox add-on for the YouTube lovers. By installing this add-on you can control the YouTube video playing by your mouse wheel. Once you get used with this add-on you will really like it. FF, REW, control volume, select quality of YouTube videos just by your Mouse wheel.
Once you installed it and open a YouTube video , the add-on will divide the video playing screen to 7 invisible sections like shown below. Each section will control different things.
Here is how you can control it
1) PAUSE/PLAY: put the mouse near the CENTRAL TOP or in the very BOTTOM of the screen and move the wheel up or down: if it's playing it will PAUSE or the opposite;
2) VOLUME: put the mouse near the extreme TOP RIGHT of the screen and move the wheel up to raise the volume level or the wheel down to lower the volume;
3) QUALITY: put the mouse near the extreme TOP LEFT of the screen and move the wheel up to raise the quality of the video or the wheel down to lower the quality;
4) MOVE Fast Forward/Rewind: there are 3 areas to FF/REW video:
a) put the mouse in the CENTRAL area, the video fast forwards or backwards of 3 seconds;
b) FASTER MOVE put the mouse in the LEFT area, the video FF or backwards of 15 seconds;
c) FASTEST MOVE put the mouse in the RIGHT area, the video FF or backwards of 60 seconds;
d) more, in YouTube and HTML5 videos, you can use the wheel over the timeline to seek at the desired position.
5) SHIFT+wheel: move video at steps of 1/4 of its duration OR 2x change audio (in the audio area) ; CTRL+wheel: move video at steps of 1/3 of its duration /4x change audio; (SHIFT+CTRL+wheel: 8x audio).
It will also auto pause the video when you leave the tab. You can control the settings under the section displayed below the video.
Video Mouse Wheel by franketto is a handy Firefox extension.
The issue I found with the extension is that when there is an ad (full screen, which you cant forward) this extension will not work. If you are using extensions like AdBlockPlus you can avoid this issue too.