video and mp3 files don't compress very much if at all..
with that said you can try this...
To compress a digital media file to make it smaller, you can convert it to a Windows Media file using Windows Media Encoder. The encoder is often thought of as a tool for compressing files that can be streamed over networks, however, you can also use compression to simply make file sizes smaller, so you can fit more of them on a hard disk.
To encode a file to make it smaller, do the following:
1.In Windows Media Encoder, click the New Session taskbar button.
2.Click Convert a File, and then enter the following information in the New Session Wizard:
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File Selection. Enter the names and path of the source and output files.
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Content Distribution. Select File download (computer playback).
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Encoding Options. Choose the level of quality that you want for the audio and video by selecting how you will use the file. Note the bit rate after making a selection; the higher the quality, the higher the bit rate, and the larger the file.
3.Review your settings, and then click Finish.
4.On the taskbar, click the Start Encoding button.
Play back the file and check for quality. Then, check the size of the file in Windows Explorer. You can change encoding options (bit rate) and re-encode the file if necessary, to find the balance that you need between quality and file size.