I think I have a clip of zooming somewhere on my harddrive but I don't remember if it's in 1080p. I'll post it ASAP.
As I don't have this camera no more, I can only explain the focus lock feature. To make it a bit easier to understand I have added a pic with explanation.
The thing is that this AF lock function works best when recording a static object/subject or with very little movement. To much movement infront camera or changing the position of the camera too much will blur the video. So it's use is somewhat limited as you cannot the focus while recording like with manual controlled focuses.