Yes, they will certainly get seen by people viewing your Facebook page but will they get seen by the people who prefer the YouTube platform over Facebook and, more importantly, will they get the same exposure from the search engines?
A growing force in getting your business ranked, particularly when it comes to Google, is VSEO - video search engine optimisation. Rather than just uploading them to your website or Facebook page, a YouTube account allows you to optimise your business videos properly so that you get the full value from them.
Using the keywords you have identified for your product or service, you need to fully complete the title, description and keyword sections for each individual video, as well as using the geotagging function so that Google knows this video relates to your business address. Make sure you put your url into the description so that people who enjoyed watching can click back to your site, as well as getting yourself a link from YouTube. January 2011 edit: Having said that, YouTube links are nofollow - this means Google does not give any juice back to your site from the huge authority of YouTube but it is always good to have a mix of nofollow and dofollow links.
If you've uploaded your videos to your YouTube site, you can then use the embed code to put them onto your website and every time someone watches the video on the site, it equates to a view on the YouTube account helping to prove the popularity of your YouTube site. They can also be manually posted to your Facebook wall or automatically linked to it through one of the Involver apps.
The value of this optimisation is definitely borne out by the video I have done for Essex Local SEO Services. Searching from my location in Essex, my video appears at position number 3 for that search term underneath two of my site's pages. And we're talking the 'Everything' section of the Google SERPs, not the exclusive section for Video results. This 'weighting' of keyword-relevant videos adds a whole extra dimension to the search results page and, currently, works better than many Facebook pages for ranking on Google because of their association with YouTube.
July 2012 edit - It's now dropped to midway down page 2 on the Web results but it's still top of the Video SERPs