I'm sure it is a serious question; a serious question that gets asked in one form or another on this board several times each day. The problem with this particular serious question is that it gives the distinct impression that the poster can't be bothered to do any of their own research. Since they've posted here, they obviously have Internet access, therefore, plugging a phrase such as "DSLR with HD Video" into a search-engine would have given a starting point. A further query such as "<Camera> review" would provide a wealth of information.
Had the OP done a little work and posted a question with sufficient information, such as "I have $XXX to spend on a camera and lenses for a business I want to start centered around <type of photography>. I am considering cameras X, Y, and Z - what do you recommend?" I am willing to be that there would have been a slew of detailed, useful posts.
The simple fact is, many of the knowledgeable posters here don't see a lot of point in doing someone's work for them. They are more than willing to help, but not to do all the work.
+1, but in addition... there really is NO answering this question.
There are a few variables... like if the shooter-to-be is going to be doing a lot of low light photography, then high-ISO capabilities and full frame is likely key. Lots of sports, frame rate will be important, etc.
Aside from that it's generally about budget. A Nikon D40 will "work" for almost anything, but then so will a D3x. If you buy a D3x, you'll have fewer limitations than you will with a D40... but can you afford it?
Not to mention... can you really use it? Spending a metric ton of cash on some "really sweet glass" isn't going to do a whole heck of a lot for you if you don't know what you really need. Example... I know someone who bought a 70-200 2.8 VR... only to find out that what they REALLY needed for their business was a wide angle. Whoops.
Or someone else who spent tons of money on that super-fast lens, but it turns out they are always outside in bright light and their camera wasn't fast enough to keep up with their sports shooting... aaaaaaaaaaaaaaaaaaaaand they were out of money. Whoops.
The point is don't go asserting what people need to do until you have the foggiest notion on what they need or you'll be doing everyone a disservice.
And for the record, I am a professional, I do buy some very high quality gear to do my work, and I know the value of it... but I also know how to use it.