Dunno about Spinervals sorry, but have you checked out
the Sufferfest?
They are downloadable, so no need to go out and buy DVDs. Image Quality is good, soundtrack is all unsigned bands but pretty good.
I have "The Downward Spiral" and it's pretty tough, it's a descending interval session. The rest footage is a little repetitive, but the warm up footage is a helmet cam DH run of Strommers which is great.
Edit - just looked up Spinervals and they are $29 RRP. Sufferfest is $12 - Bonus :clap2: