Good idea, but I think the issue is, did it air long enough for enough people to have heard of it that it would ever get checked out?
I still think a key mistake was changing the look of the characters in season 2 after having released the season 1 McDonald's toys, though evidently the cancellation was somehwat inevitable. Still, my point is that I'm afraid that it didn't build enough of a fan base in two years to create enough of a voice to overturn the cancellation.
The thing I like about your idea is that there's a chance, however small, that a few curious kids here and there would pick it up, tell their friends, and then it might snowball. (Plus, who would can argue with donations to libraries?)
Sending copies of the DVDs to network execs might have an effect if enough people did it...but look at the rate of postings in this section and, well, .... not to mention I'm sure network execs have all sorts of staff to filter their mail...
No, what we really need is Braniac 5 to construct a computer virus that would send randomly re-worded emails (that each still mean "bring back the LSH cartoon") from millions of different user accounts to the network execs, filling up their Inboxes.
wherefore art thou, Brainy?