Yeah, I agree that the title is somewhat misleading, there's no such thing as "Safest" crypto as we all know that it's very volatile, and also fluctuates in short amount of time. That's why is really hard to give advises here. Maybe choose in the top 10 altcoins and then watch how it will perform. You need to play a lot in this markets and then see how it's going to fit in your goal, short or long term and your risk appetite as well.
First of all, one has to say that no cryptocurrency can be called "safe". All of them are high risk investments and before investing in any coin, one should always do a lot of research and really think through if it's worth investing or not.
If one wants to compare the different coins out there to each other, one could say that Bitcoin should be the safest to invest in, since it's by far the top coin out there. My additional choices would be coins like Ethereum or Cardano, but compared to other investments like stocks, gold or treasuries all of these are high risk and not "safe" in anyway.
That's why you should always DYOR before investing in any cryptocurrency.Don't get fooled my missleading titles of a Youtube video.