Hi TheRealMacAddict & welcome to macosx
You haven't specified how you initially went about setting these prefs so I need to go through this:
When Firefox is first launched, it displays a box notifying you that it detected that it isn't the default browser and asks you if you would like to make it the default browser
( I'm using FF version 3.0.3 so depending on the version you have you may/may not actually see the same box as I)
There is also a tick box in this window giving you the option to disable the showing of it each and every time you launch FF. If you chose not to make it your default browser and then ticked the box to never show the choice again ... then you can click the "Check Now" button in the above image which is in Firefox Preferences.
With regards to those apps that you specifically want to have manage your video & image files, this is handled through the
"Get Info" window for each file type. You should only need to do this once for each file type ...
Highlight a video file and press Command + I to bring up the
"Get Info" on the file. In the
"Open With" section, click on the drop-down menu and select the app you want. Once you have your selection click on the
"Change All" button and follow the prompts. Close the
"Get Info" window and follow the same method again, to set the default app to manage your images.
If you have already done the above and are still having problems each time you log in/boot, then you may need to check the details at the bottom of the "Get Info" window, in the "Ownership & Permissions" section. Click on the disclosure triangle if you can't see any information about your permissions on the file. There is also a "Details" section below, where you can change the permissions if you have the Administrator username & password details. Just click on the padlock (if it's locked) otherwise just change the permissions.
It probably would be worth running Disc Utility to repair Permissions too ...
(Applications ~> Utilities ~> Disc Utility)
