Could I suggest to have the default record with centre point be the default record and it might or might not act as the first record of the clip on the effect's time-line. The reason being is that if I need to start the zooming of a clip at the beginning and changed the default x,y and zooming factor on the first record, the centre point is lost, and I lost the centre referenced point. There are two ways out of this. One is to maintain the current implementation, but make it so that the first record, which hold the centre point of the screen always be there - as default record - and if the first record was zoomed in and the location is changed, the rendering engine would ignore the first default record if its timing is identical to the next record in the effect's time-line, and start rendering the next record instead. The second is to add a guide on the screen so users will always know where the centre point is.

Regards