Hi mac user,
Please contact our Support Team and await a reply to help with your issue if you haven't already.
http://www.macprovideo.com/support/
Also, which videos are you having trouble watching? All of them or some from a particular tutorial?
I've just this minute started NEDweb and clicked on Final Cut 101 and clicked on a video. It started playback immediately... barely had to wait 4 seconds. Tried it with the Remixing in Ableton Live title and same success.
Bear in mind I'm simultaneously downloading a large collection of files and I'm using my home broadband service in the UK. The connection here is fine - which means that the MPV servers are firing on all cylinders just fine too...
There must be an explanation for this... and I of course appreciate your frustration... but please wait until our Support team are back on Monday so that can help diagnose exactly what is going on and why.
Kind Regards,
Rounik