I finally chanced onto this page :
http://www.nch.com.au/action/reginfo.html#prism
Prism
Plus Edition: This Prism license class supports all video formats except for MPEG2.
Plus MPEG2 Edition: This Prism license class supports all video formats including MPEG2
VideoPad
The "VideoPad Pro Edition Registration" lets you use a single installation of VideoPad (on a single computer) without restrictions.
The basic version of VideoPad has all the features of VideoPad Pro but after 14 days trial the range of export formats will be limited to .avi, .wmv, .asf and DVD.