Just stick to one two three four for now, whilst also practicing the Strumming patterns as they come up. These things will blend eventually, and when you've finished the course, consolidating it will probably include going back and putting in some of the more advanced patterns.
Ymmv, but for me, the cream of that strumming DVD is already in the bc, in the form of the strumming patterns. If you are evperiencing difficulties in strumming, and want a remedial deep dive, then go for it. If, especially after learning #9, Old Faithful, you want more, check out the DVD.
I found the second volume, however, extremely helpful for 16th note strumming, which comes in in the IM.