Board Game Arena

I've watched a few videos on this one (Blue Cocker Games on YouTube has excellent videos on the whole series), but I still just don't get it. Any suggestions on other videos that might explain it like I'm five? (I'm better with videos than with reading rules, when it comes to games.)

It's a tricky one, I try to focus on containing the viruses while reaching the missions, that seems to work nicely. But it's sometimes hard to predict in which order the viruses will trigger.