I have NickyTube.com which is a 5 letter as you requested.
I also have longer ones as well.
TemptressTube.com
CowgirlTube.com
NymphomanicTube.com
SexiiTube.com (Google Exact Matches for "sexii": 836,000)
DoujinTube (Google Exact Matches for "doujin": 135,000)
Contact:
[email protected]