@AVIL, 2.6 Has planar YUY2, it is called YV16.
@Fizick, Yes I got confused with many archived sources. I have 1.8.4 but stupidly was reading an old 1.4.8 source
sorry for causing any panic attack.
Yes I now agree, the MVPrepare type approach, is a very favourable approach. I changed my post above 2 times as I read more source, so some is not quite relevant anymore.
I do not think my internal pseudo clip idea is that good any more. For the future it may be desirable to use external filters (i.e NNEDI, etc) to generate/calculate the superframe clips, so I think it would be helpful make the superframe data regular clips where possible.
As tsp says for the metadata just put the data or a pointer to the data in the MVPrepare returned frame.