According to Sony, there are some issues in the digital photo-video sensor of the Alpha 33 and Alpha 55. When used continuously, it can overheat.
After a few minutes of use (mostly in video mode, but possibly in LiveView too), the sensor will overheat (effect is unclear). The best (albeit partial) solution is to stop using the Image Stabilization. As you can see in the table above, it increase the time available.