yes, in the past I was programming on different languages from Asm x86 to ABAP/4, and they did not have regular expression functionality) so I was simply not familiar with this, thus it looked unreadable for me at that time.

It's not hard to understand, all you have to do is write a comment explaining what it does and you can also tell by looking at the "http" what it is that we are looking for.

Yes, this is simple enough regexp for attention

it's a pretty simple regexp. I think, I would use something like that in real code.

looks cool, but unreadable ) such a code will be hard to maintain by someone else.... not sure if it should be the best practice in a real world