All videos uploaded to YouTube have a 100MB file size limit. The longer the video is, the more compression will be required to fit it into that size. For that reason, most videos on YouTube are under five minutes long.
In addition, there is a 10-minute length limit for all videos unless you have a 10+ Minute account. If you have a 10+ Minute account, the length limit is lifted, but the file size limit stays at 100MB.