You don't have to be staying at the campground to go to the campfire/movie. The easiest way to get there is take a bus to the MK and then the boat to Ft Wilderness. It's around a half mile walk to the campfire, or you can take one of the internal campground buses and get off at the Meadows Complex stop. As you're walking to the front of the Meadows trading post the campfire/movie takes place to the left past the bike barn (coming across the back side of the complex the campfire is to the right as you pass the pool).
You could also take your resort bus to DTD, transfer to the Ft Wilderness bus, get off at the Outpost at Ft Wilderness and then take an internal campground bus to the Meadows. To walk from the Outpost to the campfire would probably be around a half mile also. Just walk straight through the campground and you'll come to the Meadows complex. But trust me, the boat is a lot more fun. I'd allow at least an hour and a half to get there from your resort. If it doesn't take that long you can visit the petting zoo at the Settlement, or get a cold beverage and sit on the porch in a rocking chair at Crocketts Tavern/Pioneer Hall (where the Hoop Dee Doo is). They also have wagon rides, carriage rides and horse back riding (all for a price of course, but the campfire/movie are free, just not the marshmallows/hot dogs).
Depending on the time of year, the campfire/movie start at different times. Chip and Dale come to the campfire and you can roast marshmallows/hot dogs etc. You can bring your own or buy them there (but they're kind of pricey, it wouldn't be Disney if they weren't). After the campfire, there is a Disney movie shown on an outdoor screen. The movie changes daily and the schedule is posted a few weeks in advance, although I can't remember where to get the schedule. If you stay at the campground, they give you the line up when you check in.
It's a great way to spend an inexpensive evening. Getting back to your resort just do the opposite. But you need to make sure the MK hasn't been closed too long that the buses are not running there any more. If it has closed early, you'll need to bus to DTD and then to your resort.
Of course, if money isn't too tight, you can pay a cabbie $10 to take you back to your resort. Just call one on your cell phone and it's door to door service.