Why do some videos load really fast on YouTube, but others load at a crawl?

I checked to see if it was just my connection randomly having problems or whatever, but that’s not it. Two 9-minute videos by the same author, about the same length. One would load in about 2 minutes, the other is about 15% done in an hour. Close browser, try loading in a different order, but the 2-minute loading video still loads fast, the other still loads at a glacial pace. Try again the next day. First clear my cache (in case that was it). Fast video loads fast, slow video loads like a snail, yet again.

Is there any reason for this? Are they on different servers or something?

Judging by the differing addresses that come up when the videos download, I’d say you hit the nail on the head. Vids uploaded by the same person often appear to take differing lengths of time to download.

The fact that the clips are of the same duration does not immediately imply the files are of the same size, they could be of very different sizes. You can search the cache, locate the files and check their sizes.

Just checked, the sizes are not noticeably different.

The reason is definitely different servers. If the particular server the clip is on has a heavy load at that time then you will see a notable reduction in speed.

Yeah, but he ran the experiment on several different occassions. My bet is that the slow download was from a truly slower computer, not merely a busier computer.

And some are downloading other nastier things as a free bonus.

Really? I’ve never had anything nasty downloaded from a YouTube server, and I must have watched thousands of vids there.

Anybody else?

YouTube, for the most part, buys a huge number of identical machines. There really aren’t any “fast” or “slow” machines in their farms, at least by hardware. I would suspect network or config problems, or a problem with caching of that particular video on their servers.