"This game does not support PAL-50"

It's been a long time but if I remember you need to try these steps:

2. Select Console Settings, and then press the A button.
3. Select Display, and then press the A button.
4. Select PAL settings, and then press the A button.
5. Select PAL-60, and then press the A button.
6. When you are prompted to keep these new settings, confirm the settings, and then press the A button.

You going need the orginal red, yellow, and white wire that came with your xbox 360 along with a hdmi cord  

Connect your xbox 360 color coded cord to the xbox and tv and then:

Click on system

Then console setting

Click on Display

Then Pal Setting

Click on PAL 60

Then confirm

Next take out the color coded wire and plug in your hdmi then:

Click on system
Then console setting
Click on display
From there you should see your current setting is set at 720p.  Dont do nothing.  Just go back to home and you should be able to play them games.