slug length counter bumps slug over max_length limit

When creating multiple videos with the same title, the unique counter appended to the slug bumps the entire thing over the max_length of 50 chars. related to #249
Hmm, now I'm wondering how readable this alternate approach is. I was worried what I suggested was going to be unfriendly for future readers, and was going to ask about that. If I try a variation on it, do you think it will end up being more confusing than what is in the method now? I prefer readable.