I'm just wondering why YouTube URL is so ugly (i.e unreadable and not friendly to search engines). Why they don't care about SEO? My friend said that it's because they are the top website now. But how about in the past?
Every video has a unique ID, so in a similar vein to this site, it needs to be in the URL.
YouTube was started by a couple of guys who were more concerned with a great and useful site, and probably didn't know much about SEO. YouTube is a perfect example of how having an awesome site is way more important than worrying over tiny details. But once YouTube became popular, it was not worth changing the URL structure since it would break the millions of videos they already had*.
Now they are owned by Google (and possibly before then) video results are given special treatment in search results and are ranked quite differently. You won't see the page of a YouTube video listed in search results with the same style as regular pages. So the URL almost certainly has zero effect on the ranking.
Having said that, some would argue it's still be better for users to have a static-looking URL like
* by "break" I mean to the extent that they will not be the perfect correct URLs - YT could obviously redirect to the right URL.
There is beauty in uniqueness. Every media object uploaded to Youtube is given a unique identifier so it can be located. This is one area where an SEO friendly link is mostly useless. Think of 20,000 people all trying to name their video youtube.com/my-really-cute-dancing-kitty.
The SEO is in the video description and tagging and everything else Youtube requires you to fill in when you upload the video. If you're worried about SEOing your video, these are what Google Youtube uses to find yet another copy of the same darn video that's gone viral.
Go play around with vimeo.com, et. al. They tend to worry about assigning unique identifiers, just like Youtube, so the video may be located and even uglier links if you view it that way. The only time you worry about SEO friendly URLs is if you're hosting your own video on your own website.
I don't believe in the theories about unique URL being the reason. Seriously guys, the amount of videos is massive, but there are tons of ways around this that most middle-level developers themselves know!
They could have just used:
Unique canonical URLs per video (like URL doesn't change by changing video information, or at least providing SEO friendly redirects) are also not special issues. We all have been dealing with them easily.
I think earlier when Youtube started it really didn't matter as search wasn't as sophisticated as now, so, it got low priority than other things. Their real advantage is that they started too early you know.
By the time search have become big, they were already the number 1 source. In no specific order, people like Google wrote custom code to check Youtube (specifically) for videos (even before they owned them). Facebook wrote custom code to display video previews only for them when it started. Google made them, making search even becoming an internal integration, etc...
They don't need to go to searches. Searches go to them and write custom code for their specific website. This might be why there is no good ROI of spending money (dev man days) in changing how URLs work, especially given the age of Youtube, like any other very big "legacy" app developed over years, you wouldn't expect such a core part to be the most straight forward to change. It's possible, but there is likely not enough return of it.