I got videos from the library as well as reading every review on Amazon. I bought lots and really only use 2 or 3 that really suited me - it may take a bit of trial and error for you to find ones that you love.
For hatha yoga - I use 'Learn Yoga' - it is an old video that has been re-released on DVD. There are 2 workouts - a 55minute Beginners and a 1.5 hour 'general'. Class. I love both - they take you through each pose and hold it long enough to really feel a stretch and increase strength. The beginners class is still a challange - especially if you have been doing yoga then you can adjust the pose to suit your ability.
For a more athletic workout I use Baron Babtiste's Journey into Power level 2. He has many DVD's but based on review I tried this one and love it! It is power vinyasa yoga - you will sweat and shake - but you feel great at the end. It is about 50 minutes long. the Level 1 is similar but shorter.
Some others that I do occasionally are by Rodney Yee. I don't have them here with me to tell you the exact ones but one is 'intermediate' and the other is a Power Yoga. He is good - but I often find he talks a bit too much and I lose focus.
I've tried Anna Forest (too strange for me), Shiva Rea - too 'arty' Brian Kest - good but I just preferred the Baron.
I've also done a few Ashtanga classes and have the John Scot and David Swensen DVD's. Since Ashtanga is a set sequence there isn't much difference. I've only watched these as I haven't practised ashtanga enough to go through the sequence as quickly as they do. I needed to pausse the DVD too much. I think for Ashtanga its best to go to a class and once you know the sequence you don't actually need a DVD anyway.
If you find any that you really like please let us know