Pretty simple to make something like that. Can you imagine coming up onto a town in low light, and then seeing 7-8 Molotov's coming through the air at you? Just screams awesome 
Yeah, I don't really see that as a truly viable weapon, unless you practice enough to get the precise distance and are very accurate. Molotovs' area of effect is limited, not like explosive ordinance where you have shrapnel and shock spread over a significant area. I don't see it working unless you had it in a rather enclosed area, and then having a catapult probably wouldn't be feasible due to size and maneuverability.
I dunno man. I mean, if I was coming upon a town, and flames started to explode around me, I'd probably run like fuck away.
You're also not a wolf, bro. A determined wolf probably isn't going to let a few molotov cocktails ruin his plans. He'll adjust his strategy and either continue or fall back, regroup, adapt, and proceed to overcome. I'm not saying it wouldn't work in some cases...it's just not going to work in many cases, therefore I wouldn't invest effort into it unless there is literally nothing else better to do and spare resources are lying around.
