It looks like Bernie Sanders is contradicting himself here, but that is not really the case.
In the top picture, he is talking about absolute merit. He is saying Hillary Clinton is bad compared to some kind of absolute standard.
In the bottom picture, he is talking about relative merit. One doesn’t need to think Hillary Clinton is going to make a good president to support her. One merely needs to think that we’d get a major party candidate, and that she is better than Trump. That is a much lower standard.