This is a link to the video:
http://www.youtube.com/watch?v=THlwDf4zDDo
When taking long subs of some DSOs the brighter area (eg. the core of M42) gets overexposed - possibly saturated, which removes all the detail.
One way to correct this is to take another image with much shorter subs - specifically to capture the detail of the brighter areas. You then use masks in photoshop to create a composite image using the longer exposed fainter details and the shorter exposures of the bright regions. You stack both sets of exposures separately (eg. in DSS) then use photoshop to combine the two (or more) images.
It takes time - but the great images you see don't just happen, there is a lot of processing time in some of those shots. Too much effort for me - for now I'm happy with short exposures and quick processing, but I am learning more and if we ever get some decent clear skies in Melbourne I'll take some longer exposures too.
I have seen images of M42 where the person had taken 4 separate sets of exposures with varying sub lengths to even out the detail.
I don't know if there are other methods that are easier?
Regards,
Tony.