Harm, I wish I knew what more info is important in order to find a solution, but let me guess.
I use a Sony HVR-V1P from which I play the HDV material.
Settings as per attached files.
When I have capture format set as Quicktime, no problem.
Model Name: MacBook Pro
Model Identifier: MacBookPro5,2
Processor Name: Intel Core 2 Duo
Processor Speed: 2.93 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 6 MB
Memory: 4 GB
Bus Speed: 1.07 GHz
Boot ROM Version: MBP52.008E.B00
SMC Version (system): 1.42f4
The problem was that the Sony HVR-V1P was set to down convert to DV. Everything fine now.