For DOS games, DOSBox's built-in recording functions are pretty sweet. Just make sure you have a fixed cycles count set no matter what, as the auto and max settings will cause the recording to jitter whenever the game itself does, whereas with a fixed cycles count, the game is recorded perfectly, even if your system isn't powerful enough to actually play the game at the proper speed while recording it. ;)
Which means it's good if you're gonna overlay audio AFTER recording.
For streaming or recording footage at the same time as you record a voiceover, you absolutely need a powerful system, or two systems with one capturing footage from the other. You may want to invest in a capture device, or upgrade your system if you prefer to stick with software capturing.
I've been looking into Bandicam for my own recording purposes outside of DOSBox as my new system can run circles around my previous one. The unregistered version works pretty well for me, though I had to tweak the heck out of its settings to get the right balance of recording quality with codecs that would work for me. If you're just trying to grab a small window, you may also want to try VirtualDub's screen-capture capabilities, though it can be very tricky to set up properly.
As for audio... that's a tricky one. Some audio chipsets nowadays are hardwired to make it difficult to record directly from them, I think due to pressure from the music industry to help prevent pirating. If that's the case and nothing you try in terms of software and driver settings lets you record what's being sent to your speakers, buy yourself a short little male-to-male stereo phono cord and run it from the speaker or line-out port on your computer to the line-in or mic port. Might seem silly, but it worked in the past with much older hardware and I can't imagine why it wouldn't work now. (Unless those ports are defective or screwy. My previous system had issues with its Mic port and picked up massive amounts of static from it.)
--- Kris Asick (Gemini)
--- Pixelmusement Website: www.pixelships.com
--- Ancient DOS Games Webshow: www.pixelships.com/adg