Hi
I use VideoReDo to create MPEG2 Streams and then use and then use VirtualDub-MPEG2 to convert the MPEG 2 Streams into compressed AVI files using normally the DIVX Codec. They are both pieces of Freeware so just PM me and i can give you links to them and also PM if you need any more help. Both pieces of software allow you to cut the video so you can create those 30 sec clips you want to

Hope that helps you!!