I have both of the DVDs you mention, and I think that they are both indispensible. Troels' is of course geared towards model railroading, and his technique of using artist's acrylics on structures (especially roofs) is worth the DVD cost alone in my opinion. Plus, his inexpensive methods for building construction and painting will save me much more in kit costs than the DVD! Not to mention the fact that the many shots of his fabulous layout are great eye candy.
As for Mig Jimenez' DVDs, I recommend the AVF Acrylics Techniques that you mention and the Weathering With Enamels DVDs, both of which are available from AK Interactive. These are very well produced and are treasure troves of techniques by one of the most respected model builders (and model painters) in the world today. It is fascinating to see how by varying your technique you can achieve very similar realistic weathering results with either acrylics or enamels.
I also have Mig's pigment DVD ("FAQ 1" from Mig Productions), and while I think this is a very good overview of pigment techniques I do not rate it as high as the other three DVDs.
...and yeah, I am kind of a DVD nut!