One easy technique is to create a transparent PNG or PSD image overlay on a track above, with a neutral gray spot just a tiny bit smaller than the dust speck. At least it won't look as objectionable as a white speck, and may not get noticed at all by your viewers.

You can post a screenshot if you would like more ideas.

If you want to work with VEGAS only, and the spot is not too big, you could simply create a mask around the spot with the "pan&crop" tool, apply the mask to fx only ( select "yes" from that option in "pan&crop"), and add a blur effect, like Gaussian blur, adjusting its parameters until you get a desirable result.

Another pan/crop suggestion - copy the video on to the next lower track and then in pan/crop on the video on the upper track, zoom right in so that you can clearly see the dust spot and create a small mask around it and then change the path mode to negative. The masked area will now see the video on the lower track. On that lower track video, use pan/crop to shift the image marginally L, R up or down so that the masked area on the upper track will see adjacent image pixels rather than the dust sport.

Oldie, but a goody.

 

Oil on my sensor…

what is delogo? is it a plug in for vegas? where do i get it from?