We've already seen some of the adventures of young Adama during that war in the television movie Razor and we also get to enjoy his childhood exploits in the prequel series Caprica. Another spin-off seems like overkill. Caprica worked because it was done in a different but equally enjoyable genre about the origins of the Cylons. This concept seems like just another space war.
The script to the online series is being done by 'Star Trek' vet and co-executive producer of BSG and Caprica Michael Taylor, so it will likely be good. As an online-only limited series it might work. Just don't turn it into yet another series, Syfy. If you milk the cow too much, it will die.