You just bought a Seagate FreeAgent Theater plus Media Player. the product specifications stipulate that it will play flash video and audio video interleaved formats but yours did not play those formats. You used a software program WinAVI Video Converter verion 10.5 to convert to Microsoft Windows media video format, but a machine did not also play these Microsoft Windows media videos.
However, it did play Microsoft Windows media video files you downloaded directly from YouTube. What should you do to make it play flash video, audio video interleaved and converted Microsoft Windows media videos? You will want to install a FreeAgent Theater+ firmware update and FreeAgent Theater synchronization software. If that does not resolve your issue, you can try to find some conversion software that will convert playable videos as other people have this issue as well.
You will need to install that firmware software on to your media player. Synchronization software is then installed on your Microsoft Windows Vista operating system based computer. Both of those uniform resource locator web page links have installation instructions included.
You will need a universal serial bus memory stick in order to perform that firmware software upgrade. If you do not have one then you will not be able to upgrade that device firmware. You can install that Theater Synchronization software on a Microsoft Windows Vista operating system based computer first in order to see if that helps instead.
You see that firmware update is more complicated to perform. You can download this free video converter software. These instructions were written for Microsoft Windows Vista operating system, but can certainly be uses possibly with other Microsoft operating systems.