As a long time reader and paying customer of Luminous-Landscape, I've been understanding and willing to put up with a bit of inconvenience on "Opening Day" for previous videos. The value you provide has always been worth the wait.
However, I would like to add my voice to others - probably your greatest fans - and urge you to consider a better strategy to cope with the peak traffic / self-induced DDOS that occurs with the release of a new series. I believe increased competition in the video tutorial market will limit the number of customers who are willing to continue putting up with the current frustration. Surely there are vendors (Amazon S3) that can provide the short-term help you need to provide a better customer experience?
I'm sure Chris and Michael are frustrated by this as much as anyone, but I hope the following anecdote will give you some perspective: whilst unsuccessfully trying to download your videos (paid for - in good faith - over a week ago), I was able to watch a very large number of the free LR4 episodes hosted by Julieanne Kost on Adobe TV. I watched them on my iPad (connected to 3G, so I wasn't even on the same internet connection), with no difficulty whatsoever. As a long-time Lightroom User, I am after the "what's new" / "tips and tricks" of the new version, and I feel I got that from Julieanne. Her presentations were excellent. I was left with the feeling "why have I paid for stuff that I can't even get, when I got this high-quality information for free?"
Obviously I really value the information I get from your videos with Jeff Schewe and other guests, but any unnecessary barriers to me getting the information - especially when there are viable free alternatives - is not encouraging from a business point-of-view.
Please take my comments in the spirit they are intended, that of long-term fan wanting the best for you and your readers/viewers.