Why give that link juice to YouTube?  Lord knows, they've got plenty of it.

Take advantage of the links you received and make them benefit your main website.  Create a landing page on your main site featuring some of the best submissions embedded on the page, and include a link to your channel if visitors want to see even more videos.  Then, 301 redirect the microsite to the landing page on your main website in order to get the link juice to pass through to your primary domain.

The only reason you'd want to redirect your microsite directly to the YouTube channel is if you don't have a main website and your YouTube channel is your main presence online.  Even then, though, I'd generally opt in the direction of leaving the microsite up and embedding some featured videos on it.  You can certainly make a page on YouTube rank decently well for a keyword, but given the lack of control you have over on-page elements, it's much more difficult than optimizing a website that you own.

I don't really do any formal reciprocal link exchanges via e-mail, but I do have a ton of success with the following method:

1.) Write a great blog post or piece of content for your own website.  Include in it links to other great blogs or resources about the topic you're writing about.

2. When the post is published, Tweet at the people whose websites you linked to and let them know that you mentioned their amazing, helpful resource in your latest post.

3. This generates a TON of retweets, and once in a while a great link back to my website from the blog/website that I mentioned.  It also helps me establish a line of communication with authoritative figures in my industry.  In short order, it puts me on their map, making future link requests much easier.

I know this isn't exactly what you're looking for, but I thought you might find it interesting.  Just my $0.02!

Will it cause harm?  Not likely.  If Google suspects the links aren't kosher, it will probably just ignore (or "devalue") the links.

As to whether it is a shady or manipulative practice - debatable.  From my perspective, I don't quite see how it is all that different from a company linking to its partners, suppliers, or customers.  The link represents a business relationship, and that relationship has value.  If I have a client in the position to get these kinds of links, for me it's a no brainer - get 'em.  At the very worst, they have no impact SEO-wise, but help with branding and referral traffic.  Google's perspective may differ.

As to why the practice might not be working out so well for you - do you run linkbuilding campaigns for the websites you develop?  Does anybody?  Do many of the websites share a C class address?

A bunch of links from websites with weak backlink profiles or the same C class addresses won't take you very far.

BONUS - a few linkbuilding tactics guaranteed to work:

• Submitting your website to high quality, relevant directories
• Running a guest blogging campaign on a number of influential web design blogs
• Creating TRULY engaging and unique content and promote it via social media