It depends on the yarn and the stitch pattern.
The felted join (also elegantly called "spit splicing")
works well on wool, not so well (if at all) on other fibers.
I generally do what Sue does: a small, neat knot. I use the two yarn ends to make the first half of a square knot on the wrong side. Several rows later I tighten or loosen the ends so that the tension is the same as the rest of the knitting, and complete the square knot. Depending on the yarn and my state of mind, I either cut the leftover ends to 1/4" or weave them individually into the back of the knitting. This is a good, simple system for cotton, linen and synthetics, and for wool that's not too thick. It's less good for lacy, open stitch patterns.
Faced with those, or with slippery ribbon yarns, I think you sort of find your own way. Practice some or all of the joins on the videos and use whatever works best in a given situation. A lot of knitting is like that -- over time you develop an arsenal of techniques and choose the join, cast-on, bind-off, increase or decrease that works for you and your project.