Steve,
All those chords are created out of the G major scale. They are most of the chord family for the key of G major (he only omitted the C major and F# diminished).
This is a concept called the harmonization of a major scale. If you take the 1st, 3rd, and 5th note of the G major scale you get a G major chord. If you take the 2nd, 4th and 6th note of the G major scale you get an A minor chord, 3rd, 5th and 7th notes create the B minor etc.
All the notes in the G major scale will sound good over the progression. You are right, though, in that sitting on certain notes of the scale may not sound good over particular chords and other notes, especially the notes within the current chord, will sound better. Just use your ear for now. Playing the G major pentatonic scale over the progression will help you avoid some of the conflicting notes. Hope that helps
John

Steve S wrote:

So even though those are minors you can still play the major notes?

Hi Steve, John has the complete answer above. I just wanted to add a thought based on your question that I’ve quoted here. The individual notes come from the G major scale, but they are not major or minor on their own… they are just tones. It’s the combination of these notes into chords that make either major or minor intervals in the chord and the corresponding sound. So, any major scale will produce both major and minor chords as you combine the notes in the way John showed above. All of them in the G major key/family. The notes from the same major scale which you play over those chords will work, with the cautions mentioned by John. Hope this helps!

Steve,
I love how Michael fleshed out my thoughts to help make the concepts clearer. The basic idea is that the G major scale made these chords so the notes of the G major scale are the notes that work. The musical term for this is that the chords are “diatonic” to the scale.
Blues is a totally different animal. The typical 1, 4, 5 chords like an A7, D7, E7 don’t actually come out of one scale. The chords are not diatonic to an A major or A minor scale. They are the V chord of, in this example, a D major scale, G major scale and an A major scale respectively. Using an A minor pentatonic scale over those 3 chords is a kind of a best fit with certain dissonances that we have come to love as the sound of the blues.
A little bit of music theory can clear a lot of this up. I really recommend looking up “harmonization of a major scale” on YouTube or checking out Brian’s essential theory course under the My Courses icon.
John

…and a very little detail: when you abbreviate minor chord names, it is best to use “m” instead of “M”. For example, use “Bm” instead of “BM” for the “B minor” chord.
You will also find them notated with a minus sign, e.g. “B-” (particularly in the Jazz Real Book).
The capital M is usually reserved for other usages – although I’ll gladly admit that chord names are (unfortunately) not completely standardized 🙁