:woohoo: I can actually answer something!!!!!
I don't have a video or know of one....someone else might know where one is.....
...but I do know that if you're knitting on straight needles, you basically just pick up the new color and knit w/it, not much more to it than that....other than the fact that you need to loosely tie the old yarn and the new yarn together, making sure that your knot is behind your work (on the wrong side).......and being careful to not pull the knot too tight....this might cause a hole.
Changing colors on circulars is trickier.....you TWIST the colors together (the new and the old) behind your work (again, arong side of fabric) and begin to knit w/the new yarn. When you're finished, you'll weave the ends in.