Sheryl, I have to answer your question in two parts.
1. The video is actually by randy adams: @randy-adams
2. I strum in a similar way to what Randy shows. The return stroke is just the reverse of the out stroke. Nothing fancy. I hold the pick a little more loosely or tightly depending on the effect I want.
For general use, I prefer a thinner (softer) pick, but I also switch to different weights for different purposes. I even use a pick cut from a plastic butter tub lid when I want something really soft. Pick choice for me also varies from isntrument to instrument.
Probably 90% of the time I use these picks, at least right now I do: http://www.amazon.com/Tortex-Guitar-Pick-Pack-418P-50/dp/B0002D0CEO . I also like the old standby fender thin plastic tortoise shell type. I got used to them playing guitar.
This is such a personal choice I suggest trying different things until you find something you are comfortable with. Also, remember that when you play, you are sitting pretty much on top of your instrument, so you hear things (like pick slap) that other people don't. Even those just a few feet away.
The greatest music is made for love, not for money -- Greg Lake
updated by @bob-reinsel: 08/03/15 03:31:12PM