It looks like you had the camera's exposure control on automatic: I think I saw the iris adjusting within a shot once or twice and you don't want that. Auto exposure will attempt to average out the scene (though it will probably give a little more weight to the centre) and high contrast, spotlit scenes like the ones you have shot here present special difficulties for auto exposure algorithms: the dark background (especially in your first shot) makes the camera think "it's dark" so it opens the iris right up, with the result that your subject (small in relation to the frame overall) is overexposed massively.
Use manual exposure - or whatever exposure control the GL2 has (for example you may be able to instruct the camera to overexpose or underexpose by 1, 2, or more exposure stops: in this example you needed to underexpose by -2 stops at least) - to set the exposure for your subject, not the background or an average of the entire scene. If you have a chance, zoom in to set your exposure on the subject, then go back to your wide shot and recompose. Keep exposure locked during a shot to avoid the iris adjusting during a shot, which always looks amateurish. Use the viewfinder instead of the LCD to check how your exposure setting looks. Keep a close eye on lighting changes as the show you're recording progresses, as you may need to bump the exposure up or down from scene to scene to compensate for lighting changes.
Last but certainly not least - experience is your best guide in these situations. The camera's brain is much, much smaller than your own and the numbers it comes up with must be considered a guide only - don't rely on the camera . Your own judgment is crucial.
Andrew.
