MSNBC's Ari Melber seemed downright gleeful at the news that vulnerable Senate Democrats have started running campaign ads touting their support for ObamaCare. Filling in for host Lawrence O'Donnell on The Last Word with Lawrence O'Donnell on Monday April 21, Melber hyped how "there are signs that President Obama's new call to run on the Affordable Care Act has gotten through to Democrats. Video cross-posted here at NewsBusters.