not been my experience mtv so far used the canon 7D and father in laws 550D and a friend came over over christmas with a nikon d90 and that did a superb job for audio and video both outdoors and indoors. keen to know which slrs you find this with as I do not think this is charecteristic of them I would say. perhaps some early dlsrs that were trying to do video as well. but dont think it is the case any more. Not surre your aware but many TV commercials and even film makers use DSLRs for hd video these days and this is for broadcast quality audio and video.
I've used the Canon 5D and 7D for both commercial broadcast and corporate production, but only where the camera is in a fixed position or tilt/pan.. no other functions.
Audio is recorded separately, as inbuilt mics in those cameras is inadequate and external audio interfacing does not work well.
Audio might be acceptable for domestic 'home video' use but try using it outdoors in the wind, several metres away from a talking head.. it's just not acceptable for professional use.
I'm certainly not disputing the PQ which can be obtained, because it can be excellent, but it comes down to the end use and the budget of the OP, which is lower-end $200-$300 for which you won't be able to buy a good digital SLR and lenses.
The larger the sensor, or in the case of higher-quality video cameras... 3 sensors.. the better the PQ.
Cheaper cameras usually have much smaller sensors than their more expensive counterparts.
Without getting too bogged down with technicalities, the OP needs to decide what PQ will be acceptable to him for his intended final use.
DVD is SD, so it's 576i or 576p.
Youtube can be whatever you want, but 720p is usually more than adequate as HD.
1920 x1080p meets the 'Full HD' criteria, but if you have low quality optics, noisy video processing, smaller-single image sensor etc, you can still have very average PQ, which is why a $50K camera with a $30K lens is going to produce far higher quality images compared to a $300 camera/lens, even though both are defined as 'Full HD'.
The same principle applies to the higher-end digital SLR's... the optics are generally better than the cheaper video cameras and they usually have larger sensors.
Sure.... great stills cameras, but video in them is designed as an 'extra' feature, not it's primary function.
Same as many video cameras can take stills as a secondary feature.
Given the OP appears to have little knowledge and experience in video production, a low budget and predominately SD output requirements, I feel a video camera would be better-suited to his needs.