Watch the 1 5 7 3 Structures online guitar lesson by Brad Carlton from Guitar Lab: Open String Universe

This lesson uses a root fifth seventh third structure on the 6th through 3rd strings combined with the 2nd and 1st strings open.

Voicing 1 is a BMaj7add4 voiced 1 5 7 3 1 4. Ionian is the only scale that fits this chord. Voicing 2 is a CMaj7 voiced 1 5 7 3 7 3. Ionian and lydian are the correct scales for this chord.