Syncopation is the key word with riff 3. It is important that you follow the accents notated within the score to achieve the correct rhythmic pulse. The meter here is 5/4 and each bar is divided into two groups of five 8th notes.
In the video, I play this section using hybrid picking with the right hand. This way is a very natural way for me to do it. Again, you can use any means necessary to achieve the desired result so experiment with as many ways as possible.