Possibly the pilot was in a sustained left banking turn and didn't realise that he was losing altitude and/or airspeed. The "Roll Right!" command was possibly to force him to go 'wings level' and maintain altitude.

Any time you bank the wings of a plane to make a turn, you have to also pull back on the stick to maintain the same amount of lift to keep you in level flight. The more you bank, the more 'back stick' you need to maintain the lift.

It's a logarithmic corellation, i.e. in a 90 degree banked turn, it is impossible (you need infinite lift) to maintain altitude.

Most aircraft get to the point where the bank is just to steep and you cannot generate enough lift to hold your altitude any longer. Pulling back on the stick some more will just end up bleeding off airspeed and putting you into a stall/spin. At that point your only recourse is to go back to 'wings level' and rebuild airspeed.

Not a pilot or engineer - but I imagine if the plane were in a "banked left" position (prolonged left roll) where altitude was being lost because of "slip" - then rolling right would restore lift / level flight

http://2bfly.com/assets/slipinbank21.png