Nice post. I think this is similar to something I've been working on.
I watched the video. I will say for myself, I was a bit underwhelmed that there didn't seem to be some usable context for his lesson. But not to say the context isn't interesting. To continue to your point...
For myself, an interval is an interval, but some intervals when played together can allude to certain tonalities, which you can probably then call a "baby chord". Here's a simple progression that can show my point:
First, you can vamp on a ii-V, in the key of G, which would be Am-D7:
For the Am chord, you can play A on the down beat, and then the interval of G-C (5th fret of D and G string) in the middle of the phrase
For the D7 chord, you can play D on the down beat, and then the interval of F#-C (4th fret of D, 5th fret of G string) in the middle of the phrase
Repeat ad naus...
Then you can move on to a ii-V-I-VI in the key of G, which would be Am-D7-G-E7:
For the Am chord, you can play A on the downbeat, and then the interval of G-C (5th fret of D and G string) in the middle of the phrase
For the D7 chord, you can play D on the downbeat, and then the interval of F#-C (4th fret of D, 5th fret of G string) in the middle of the phrase
For the G chord, you can play G on the downbeat, and then the interval of G-B (5th fret of D, 4th fret of G string) in the middle
For the E7 chord, you can play E on the downbea, and then the interval of G#-D (6th fret of D, 7th fret of G string) in the middle
Repeat ad naus....
There's so much that can be talked about just on intervals, and how the same interval can sound different, depending on the root note/chord. However, this post is already long. Hopefully this is what you were looking for.
If you haven't checked out this video yet, it may help put some context to your interval and double-stop work: