YouTube
First, make sure the file is under 100mb. Also, make sure the file is one of the following (.mov, .mpg, .wmv, or .avi). Finally, what is your connection speed?
From YouTube...
My upload's been running a long time and hasn't completed. What should I do?
Uploading a video can take several hours, depending on the length of your video and the demand on the servers. If your video upload is taking longer than 24 hours to complete, we recommend canceling the upload, checking the length and settings for your video, and uploading it again.