Ok, had some issues with the DVCPROHD frame rate converter myself.
Two things you need to look out for – the error message “The selected media file (FILE NAME) cannot be processed by this tool.
Only DVCPRO HD 720p 59.94 and 50 fps media files are supported.”
doesn’t makes sense – I read that this pops up if you don’t have the latest version of QuickTime, which could be true as it will convert it into a new .mov file – have never experience that problem myself.
However the problem I ran into is that all of a sudden the error message “error occurred during processing, unable to conform source media” even though I had successfully converted 59.94 fps to 23.98fps (shot at 720p24 setting in the HPX 500 with the scene file set to 60 frames)
I tried to reimport the same footage into a new FCP project but that didn’t help still the same error.
so I shot another test again normal 25p and then at 60frames (same settings, same camera as above) and then brought it into final cut. setup a 23.98 time line and used the DVCProHD frame rate converter (only really works when you select the clip in the browser some people write about selecting it on the timeline, never worked for me). And: it totally worked converter my 59.94 footage (check ‘remove duplicate frames’ and ‘make self-contained movie’ you can alos choose “import result into FCP) and when I dropped the converted file onto my 23.98 timeline I had wonderfully smooth slo-mo like last time I did it.
Now I imported the clips from my FCP project that didn’t want to convert files anymore. took the original clips in my new project and converted them no problem, worked too.
Then I opened my old project, in which the converter didn’t work anymore and – look at that the converter all of a sudden worked again…
so I know it’s been a while since you posted this question but since to me it seems that this is more a bug then human error and lack of knowledge I felt I still throw in my little experience also for other users…