greengeeks' recent post about QWinFF reminded me that in some now old Puppys there was a builtin application named FFConvert. shinobar developed and maintained it. It is still available from here, http://shinobar.server-on.net/puppy/opt/. But, as it's small enough to be included as an attachment under this Forum's more generous size restrictions, I've attached a copy of the last version.
Examination reveals that the only executables are bash-scripts. Consequently it is "No-Arch" and should run under any Puppy whether 32-bit or 64-bit: e.g. seems to run fine under Bionicpup64.
However, it has not be updated since 2014. So, you can't expect it to be able to handle --make use of or generate-- any codec or container not then current. For example, mkv is not recognized. However, under the "Preset" Tab a choice to select "User Defined" exists. Someone who knows what (s)he is doing may be able to extend its capabilities. Better yet, perhaps someone could publish an updated version.