Hey,
So, the situation is relatively convoluted and there isn't an absolute right answer to what best practice will be, but hopefully I can offer you some useful advice.
I'm not entirely sure what you mean by "credit" regarding YouTube videos but I assume you mean rich snippets? In this case, it is indeed true that Google don't often give out video rich snippets for embedded YouTube videos, but instead normally just provide a video result that links to the main YouTube domain - however, within the last couple of weeks they have visibly begun to occasionally offer some more rich snippets for embedded YT videos, but only for high authority blogs and where the blog provides a great deal of supporting content.
That said, you should still summit a video sitemap for any embed YT videos you put up, as you are giving google good metadata about your site that helps them to crawl it better. While you may not get the rich snippet, that does not nullify the value of the sitemap.
I'm not quite sure whether in your proposal you plan to host the versions of the videos on your own site with a third party or with YouTube? If it's the latter and you're simply proposing that the metadata on your page focus's on different terms than the YT video itself, then I would advice against it. In this instance, you almost certainly won't get a rich snippet, as in Googles eyes the embedded video will be broadlyl irrelevant to the focus of the rest of the page. However, having versions on your site hosted with a third party i.e wistia (or self hosted) and then uploading the content to YouTube, essentially as a duplicate, but targeting a different term - this can work. Whether its a good idea or not really depends on the content itself and the audience base the site has.
Another point to recommend is that you should never put promotional or commercially focused content on YouTube - always host that yourself or with a secure third party solution. The user engagement metrics on YouTube are critical in determining whether you will rank both on YT and on Google and if the videos appear algorithmically uninteresting - then your rankings will suffer. Only put content on YouTube that users who find the videos through searching on YouTube will want to watch. How-tos and funny content are great, but stay clear of product information or blatant advertising (unless you are doing PPC YouTube advertising).
Hope that's useful, let me know if you have further questions.
Phil.
Written on my iPad, on a train, so sorry for any typos!