DM800 Secondstage Bootloader 72
The bin files are for the OE to be built into the images, not for direct flashing !
As soon as DMM has testet them within images sufficiently they will show up also on dreamboxupdate as ipks or as small nfi files.
I just posted you the links that you know where they originally come from, and if your box is not online or you want to use them even with older BA versions for a backup you can download botloader 72 and put them at /MB_Images (but there you have to rename them to secondstage.gz in case of the 800/8000 loader) ! if you denn make an nfo backup with BA they will be used from there instead of downloading from there. if you then flash such a backup image it will include and install also the new loader !
If you want to keep your image in Flash - install latest BA, boot from flash, do a backup booted, get the nfi file to your PC and Flash it then you will have same image in Flash but with latest boot loader.
Then you probably should download also the latest drivers and install them to prevent possible compatibility problems.