type one or type two ?

There are two kinds of dominant seventh chords in this world ...

Those that resolve down a 5th and those that don't.

You can play more "outside/tension" tones (b9 #9 b5 #5 M7) over a dominant chord that is going to resolve and you need to play the more inside/pretty notes (9th #11th 13th) over a non-resolving/moving dominant.

This is because the V - I resolution makes the overall harmony obvious, so you can play the tones that take you further outside the key over a dominant that resolves.

In her video, Emily Remler says that she likes to keep things simple and think in terms of minor and majors. She doesn't think in terms of Mixolydian when she solos over a dominant chord, instead she just thinks of jazz/melodic minor scale.

Type 2 dominant 7th chords resolve down a 5th.

On a Type 2 dominant chord play the Jazz/Melodic minor a minor 2nd above the root

Type 1 dominant 7th chords don't resolve down a 5th

On a Type 2 dominant 7th chord play the Jazz/Melodic minor a perfect 5th above the root

Why does this work ?

Looking at a type 2 G7

Over a Type 2 we play the minor up a 5th, so over G7 this means D melodic minor

1 3 5 7 1 3 5

G7 - G B D F G B D

D melodic - D E F G A B C#

5 13 7 1 9 3 #4

D melodic has the chord tones plus the pretty tones (9 13 #4)

Now Looking at a type 1 G7

Over a Type 1 we play the minor up a minor 2nd, so over G7 this means Ab melodic minor

Ab melodic - Ab Bb Cb Db Eb F G

G7 - G B D F

1 3 5 7 1

G7 - G B D F G

Ab melodic - Ab Bb Cb Db Eb F G

b9 #9 3 b5 #5 7 1

Ab melodic has the important chord tones plus the more outside tones (b9 #9 b5 #5 )

Thanks to Emily Remler for this idea