Heh, wanted to post a comment in the shout box, although not that long, still WAY too long for the character limit set in it (could type it all, but not much of it appeared after posting. It should have a visible char limit imo), so instead of shouting like 4 times, I post it here instead ;)
@Frederikct112
/Jihao
The quality a video gets on YouTube depends on the video. A source video of (an example) 1920x1080/5mins/100mb/mp4 can look just TERRIBLE and if you download it from YouTube it could be like a 20mb file. They work with a very limited bitrate. Now, some stuff CAN look nice on YouTube, like the one in the link Frederikct112 posted to (sure, still not as good as the source, but good), that's because this video uses low frame rate, giving more bits to work with the quality per frame. Now, don't right click the movie and see what frame rate it uses, as it doesn't matter, only matters how many frames/second the actual animation updates, which is like 10fps/sec or something for most of the things in the animation. If it was a 25/30 fps animation, the quality would be much worse.