What's the point of dropping a few Benjamins on a tablet if you can't watch video on-the-go? Although much fuss has been made of Cupertino's reluctance to add Flash to its line of iOS devices, the kings of content (read: networks) are still scheming up ways to port the prime time eye candy to your portable slates. Shoring up that streaming divide are a trio of new apps from NBC, TNT and TBS that deliver full episodes of the networks' fodder to your iPad, albeit with some authentication required. Unlike other premium mobile video services, these three apps come free of charge