MPEG Joiner by DigitByte Studio is a light weight (400 kByte) MPEG video tool that will allow you to merge any number of MPEG videos into a bigger file.
The program has a very simple interface with the basics: add MPEG, Up, Down, Delete, Clear buttons. No preview or additional tools (it presents a preview button but it only opens the video in another application from your computer like for instance Windows Media Player).
The merging process is very simple, you only have to add MPEG files to the list by clicking the Add MPEG button or drag and drop them in the list, adjust file sequence, with the Up and Down buttons, insert the output file name and click the Merge button to join the files together.
This application is good if you only need to join mpeg files. There are no other tools, and it does not work with additional formats (I would not buy a $20 tool that can only do one thing with one format) but if you want to test it, It can be downloaded as a limited 30 day free demo at the developer's site (this version won't allow you to join more than three MPEG files).
Microsoft Windows 98/Me/NT/2000/XP/2003/VISTA
16MB of memory
2G free space of hard disk