I know, I even asked the guy who posted the video what the source of his information about this "new series" came from, and he told me he read them on several different sites, but couldn't remember the names of any of them (oh, that helps), but that they all said Ross told them about the idea for the new series among other future projects.
So I Googled "Little Alvin", I Googled "Mini-Munks", "Mini Alvin", "Little Munks"... all I got was stuff about the DVD movie, I didn't find a SINGLE report about a supposed series. IMDb didn't have anything, and I didn't even bother to check out WikiPedia.
I'm trying not to get excited or anything, I mean, it's JUST a rumor, though so far, most rumors have been proven true *cough*sequel*cough*.