This 2 chord progression is incredibly simple, but provides a backdrop for dynamic improvisation. You can play a wide variety of scales over this track. Try the D major, A maj pentatonic, and A blues scales over it. Notice how they all sound great harmonically, but each has it's own distinct mood and feel. You can switch between each scale on the fly for a great sounding guitar solo.
Do you recognize this common progression? It is a very classic blues sequence, a "1-4-5" 12-bar blues in G, in 6/8 time signature. Try counting along to it, 1-2-3-4-5-6, 1-2-3-4-5-6... etc. You can use the G major and G blues scales interchangably to a make great sounding, soulful blues solo. Give it a shot!
This is a great opportunity to practice changing keys mid-solo. The first part of the progression is Cmaj7-Emin7-Bmin7, which is in the keys of G major & E minor. You could play either of those scales. I recommend playing an E min pentatonic over the first part. 8 bars in, there is a harmonic shift. You hear it right? This section is Dmin7-Amin7-Gmaj, Fmaj7, which is in the keys of C major and A minor. Try playing an A min pentatonic scale over the second part.