When you record with the hv-30, you see the 'red button' as indicator that the recording has begun. Now i had some times, the 'red button' is flashing on/out, before a recording. Anyone know what it means?
Also i had some experience with missing recordings 'always at the begin' at the beginning of a tape (which had some previous shoots on it, i record over them).

I experience all these things at the beginning of trying to shoot a wedding dance, the cam is left in shootingmode for several minutes (preparing the dance/music), before the couple starts to dance.
Could it be it has to do with (see manual):
"to protect the tape and videoheads, the camcorder will enter the stop mode, if left in record/pause for 4 minutes 30 seconds, to resume recording press start/stop."

The second time now the wedding dance is nowhere to be found on the tape.
I'm beginning to doubt myself i do press the record button, but in fact i know it has something to do with the cam...don't know what.

I don't know how long you are talking about it missing, but I know that any tape based device can have a delay of up to 5 seconds. It's standard that it takes awhile for the tape to catch.

'im talking bout whole scenes, who are missing. i cannot believe i forgot to start the rec button. but i do have some happenings, the red button is flashing on/off. while normally when you record, the button alwayson from the start, i don't get it.

If you keep the camera set to "Record" for more than 4 mins 30 seconds, whist not actually recording, the camera automatically enters "Stop" mode. This is done to protect the recording heads from wear, as they are constantly spinning in Record mode, even when you are not recording and the tape is stationary. This is covered on page 24 of the PAL manual in the "Recording Movies" section and on page 84 in the "Troubleshooting" section

In "Stop" mode the tape is unthreaded, so when you next want to record, you have to wait until the tape re-threads - this is what is happening when the red dot is flashing. If you attempt to record a short scene whilst this is going on then the camera will never record it!

Almost all tape based cameras have this feature. If they did not owners would be needing new recording heads at frequent intervals.