is not the best video editor in the world anymore. It cannot handle 4K, it hates modern codecs, and it will crash if you look at an H.265 file the wrong way.
Use 7.0a if you are restoring old family DV tapes (MiniDV cameras from the early 2000s). Use modern software if you are editing 4K from an iPhone.
The "7.0a" patch did the following:
Sony Vegas 7.0a (specifically build 115) was a professional non-linear video editing software released in . This version is notable as the final release to support Windows 2000. Key Features of Version 7.0