Not sure of your problem, but it could be
(a) Not aware that you need to join the parts to see the whole video
(b) Not aware that these parts are posted in the yEnc format.
In either case, go to these sites and download free software
http://www.forteinc.com/main/homepage.php Agent is a newsreader which
will decode yEnc automatically. You may need to purchase the
commercial product to do this however.