If your musical tastes and goals are the same as (or quite similar to) when you first started out 20 years ago, if the bass you see in your head when you think of bass and/or yourself playing bass is a 5 string, then I agree with the others to just go with the 5 you already have. First part of every journey is the first step — just break it out and begin.
However, if your tastes and/or goals have changed over the years and you now more see yourself playing the kind of songs that were done on a 4, getting a 4 could be a good way to go, and would have the additional benefits that the video you saw pointed out. And if it’s possible to also keep the 5 (instead of selling it to raise funds for the 4), you’d still have the 5 around to experiment with and slowly adopt or not as you prefer.
Main thing besides just getting started is motivation. What inspires you? That includes that you don’t have start right out with your dream instrument (very, very few do), but you want to get an instrument that you are attracted to somehow, that you want to pick up and play. Like clothes — it might be a favorite t-shirt that you keep wearing cuz you like it, and it might not have been particularly expensive or "high quality" at all. Meanwhile, you might have much "better" clothes at the bottom of your drawer or back of the closet that you never wear because, yeah, no, "not really me". Others might not fit or might be damaged, so they sit unused. Same goes with basses, and just like you don’t have to be a clothes expert or fashionista to pick a t-shirt you want out of a rack, you don’t have to be an expert bassist to see something in your price range to think "Hmm, this one looks kinda cool. I want that one."
That might be why/how you originally picked out your 5-stringer, and you may very well feel the same way today, in which case you’re already set. Go for it. On the other hand, if you now look back and laugh or cringe or whatever at what your tastes were back then, then get something that suits you now. Whatever you’ll be happy to pick up and learn to play on will be good (assuming it is mechanically sound and set up appropriately).
Welcome back to bass
