Amplitude modulated wave weird display in oscilloscope
Your digital o-scope is aliasing the high frequency content of the modulated waveform. This is a common "feature" in digital oscillosopes.

You have the time base set to show the modulating signal (orange trace) and no problem here so far but the o-scope won't be sampling at its full bandwidth because it doesn't need to. If you turned the timebase up to run more quickly you'll get to a point when you start to see the carrier frequency in all its glory.

Here is a decent document that shows what happens and here's a little video you can watch.