MPEG4 video on my mac?

What software is safe to download, from what source, to view an MPEG4 video on my mac?

If the files contain "standard" MPEG-4 or MPEG-4 AVC content using common settings, then the files should play in your QT player as is. Hybrid encodes and some older MPEG-4 video files not supported by the QT Player can normally be played by the free VLC player which can be used by Mac and Windows users alike. On the other hand, some MPEG-4 using the latest generation of proprietary codecs may require the purchase of a dedicated player or codec that would be compatible with the older QT 7 or MPEG Streamclip apps. My recommendation would be to try the free VLC download if the file doesn't play in your current QT player app.