I am experiencing similar errors to those in other threads. I use MeidaCatcher to record programmes, in my case from BBC iPlayer and this records them as .flv files.
The .flv files play perfectly in the Applian FLV player, but I'd like to convert these so that we can watch the programme on a DVD player, rather than the TV screen. but no matter what I do, I cannot convert these files to any other format. Actually what happens is this: Replay Converter happily thinks it's converting, but about thirty seconds after it's tried to convert a, say, 300Mg file, I am left with an approx 500K avi, or a 1.5Mb MPeg2 file, which plays, but it is just a video saying something like:

DirectShowSource: Could not open as video or audio"
Video returned: "DirectShowsource couldn't open file [filename].flv:
An operation failed due to certification failure"
Audio returned: "DirectShowsource couldn't open file [filename].flv:
An operation failed due to certification failure"
(C:\Users\XXXX\ApddDataLocal\27XBD1234332.avs, line 1).

I understand that you cannot access BBC iPlayer, but wonder if there is anything I may be able to try to get this working?

I have just upgraded to RC3.20 (11/03/2008)

Many thanks.