[ but getting a DVD from, say, Osterlind wouldn't be such a bad idea, because it's good to see a visual how mentalism is preformed.
Which dvd from Osterlind is the best?
I hate that question, lol. What is best is all subjective. Osterlind has about 15 DVDs or so. Different DVDs contain different types of material. It really depends what types of effects you are looking for.
Just read the description of the effects and see if they fit what you are looking to do.
I own 11 of his DVDs and I love them all, although some more than others.
Osterlind's Mind Mysteries Volume 1 is universally thought of as a great DVD, so you can't go wrong with that one. If you like mental effects with cards then go for volume 2, which is his Breakthrough Card System.
Then he has DVDs with spoon bends, fork bends, blindfolds, calculators, etc. You can't go wrong with any DVD as they are material Osterlind performed for about 20 years before he decided to put them onto DVD. It all depends on what you are trying to do, so just read the effects list and descriptions.