The optimal way to approach this issue (IMO) is to not rely on Flash to distribute information critical to your site, period. But if you absolutely can't do that, the two methods I would use are a Flash support test (not a plug-in test, that is something else and unreliable) or simply a "no flash" link near the flash object in which everything in the Flash is re-laid out in HTML with animated .gifs, if necessary. (this one will still kick the alt. content error on that page.)
The first way, which still has problems, is to create the smallest Flash object possible (I think it's 18 X 18 pixels) and simply code into that object the flash url.
...<meta http-equiv="refresh" content="0; url=noflash.html"> ...
<object . . . sniffer.swf . . . >
Sniffer.swf has a single actionscript in it.
So: if the sniffer executes, it will direct to the flash url. If it does not, the meta-refresh will direct to the non-flash (alternate content) url. The biggest problem here is what this does on search engines, but I've got a few sites out there that demanded Flash and it's been working ok for a few years, and their non-flash content pages are indexing. So it appears to be sufficient.
To "return to this page" you have to be sure to either link to the TEST page and not the flash or non-flash pages, or use a script or cookie throughout the site that tracks whether flash is yes or no.