-First off, no idea what "Hole Hearted" was, but when Googling it, the only thing that came up was a song by "Extreme".
-Assuming that is it, he isn't doing an A/D string strumming thing at the start of the song.
-If you are talking about the next part of the song, ya, he is playing mainly on the A/D strings, but it's not really a strumming. If you are hitting ALL the strings when you should just be playing 2.......well the obvious solution would be to stop strumming down so far. Play it just like you would on 1 string, but hit 2 instead. Can you play the same rhythm on 1 string? If not, then you need to just work on your right hand control. It's like saying you are trying to play 1 string but are accidentally hitting 3. Well then stop moving your hand so far up and down and focus on the 1 string you should be playing.
-As far as muting goes, use your index finger on your picking hand and just lay it flat on all the strings below. That way they are all muted if you accidental hit one. You should rely on this though since you shouldn't be hitting any other strings anyways. It's there just in case you ACCIDENTALLY do.
-Lastly, he is using a 12 string guitar, so you won't get it to sound exactly like the song unless you have a 12 string.