I'm less familiar with law and more familiar with YouTube, but i'll give it a go.

DMCA has safe harbour provisions for the linking of content, simply embedding the video doesn't violate IP laws in the USA as the uploader has given YouTube license to redistribute and YouTube in turn has reissued that license to anyone who embeds their player. I'm from Canada, most of what we have on the books is from the UK (thanks) so i'm going to assume that you don't have have any IP laws that add or replace the DCMA. Forgive me for not taking the time to look it up myself, but I assume most if not all laws that will be applicable to your situation are American.

As for the second part of your question uploading content that isn't yours, or isn't in the public domain, is theft of IP and could make you liable to lawsuit. Let it be known that there isn't a single case (AFAIK) of this being pursued in the history of online video, all lawsuits have been directed at the content provider Google/Vimeo/Liveleak rather than the uploader.

I must also mention that much of IP law simply hasn't been settled in court. 'Fair Use' is a doctrine not even codified into law yet, and although there are a few cases regarding the embedding/reproduction of text based content you won't find a single one that involves online video as the few that came about were settled before making it to the bench.

As a fellow non-American internet entrepreneur i'll advise you to do what you think is right, respect your local laws, and generally disregard American (YouTube server location) laws as they are largely unenforceable in your home country. This isn't popular advice and you should weigh the risks, pros, and cons yourself.

There is also the mens rea defense in our glorious commonwealth but you've blown that by asking this question publicly, ahh another bad Canadian joke. Best of luck!