Make of this what you will, from The Hill:
GOP Group releases video of Sanders crowds
Seems that the Tea Party realizes that their interests are best served by making sure as many people as possible are aware of Bernie Sanders' popularity. Why may they want to be doing that? The article doesn't say.
I have a theory. As we have seen here, there are a couple groups of Bernie supporters. There are strong Democrats who think Bernie is the best candidate and advocate for him, but also recognize that the other Dem candidates are each light years better than the best Republican and will support the eventual nominee. Then there are those who are very frequent diary writers and commenters, who "concern troll" constantly. The success of Bernie is not so much used to support Bernie but to justify repeating right-wing talking points against Hillary. These "B partiers" seem to have more in common with the Tea party than with those of us advocating for a liberal agenda. This group willfully ignores the policy positions that Hillary stakes out, instead saying over and over again that she is not liberal, cannot be trusted, etc. These are the folks that say they would rather chew off their own hands than vote for Hillary Clinton. I think many of these B partiers are actual Tea Partiers who are paid to sew discord among us, but there are genuinely those who believe that having Hillary Clinton lose, were she the nominee, would be better for us long term than having her win, in the hopes that the Democratic party would move farther left in the future. (Why else would these folks pledge not to vote for her in the general were she the nominee?)
So the Tea Party is hoping to fuel the B party movement in the hopes that it topples Hillary.
It could totally backfire - spending their PAC money to promote Bernie Sanders could introduce more people to the views espoused by Bernie, and Hillary, on income inequality, voting rights, etc.
However, more likely, the Tea Party knows that the media eats up every opportunity to trash HRC and this will generate some anti-Hillary coverage.
I think it is generally a risk to meddle in the opponents' primary - it could backfire. But the Tea Party has zillions of dollars - don't think this cost much to produce and likely will rely on earned media coverage and word of mouth vs. paying for any views.