I want to watch an entire YouTube playlist at full screen. The playlist consists of nine videos and every video's quality can be chosen from 240p all the way to 1080p. I want to view the playlist at 720p, but every time I choose it while watching one video it reverts back to 1080p when it switches to the next video, though in my "Settings" I have "always play at HD" unchecked. I want to play it at 720p because my internet connection can never play 1080p properly.
Is there a way to watch the playlist at a constant quality throughout?
There aren't a lot of options for you on this one, but check out Youtube's Playback Setup page (you'll need to be logged in). This will allow you to unselect the option for always playing the highest quality video according to your player size.
This is the setting that changes your video quality selection with each video load (it's video specific, not channel/playlist specific).
There is also SmartVideo for YouTube, which I prefer. It has more options, like forced buffering of videos, stop YouTube from changing the quality of the video when you want to see it full screen, or even to stop or start the video once you click on the link or when to play if X percent of video has already been buffered.