Uploading video is a fairly bandwidth intensive task. Uploading videos can take a long time depending on your connection and the size of your video. Let's explore a common scenario.
We've found through testing that many DSL and Cable connections are limited to 60K/sec. You're trying to upload a video that is 500MB. There are 1024 KBs in one MB. At a rate of 60K/sec it will take you 500MB *1024KB per MB / 60. This equals 142 minutes or about 2.5 hours.
However in real life situations, upload speeds are usually slower than what your peak, optimal speed might be. Also if you're using your internet connection at all, uploading or download other files or if others are on your network, you'll see slower speeds. So in reality, a 500MB file might take 4 to 5 hours to upload.
If you don't want to wait around for your uploads to complete, you should queue them up in the Multi File Uploader and let them run overnight.
A note on K (kilobytes) vs k (kilobits). For an explaination of bits vs bytes, please check out this helpful article: http://compnetworking.about.com/cs/basicnetworking/f/bitsandbytes.htm