a. You can certainly control how your copyright material is used. There are many ways to exercise this control as a copyright owner, so you should give it some thought and then communicate your policy clearly on your blog. There is no fixed format that a licence must take. The more important thing is to communicate your intention clearly. For example, do you want your work to be freely distributed without any conditions, to maximise your reach without bothering about dollars and cents? Or do you want to restrict use to only non-commercial distribution and copying? Will you allow others to modify your work? Under what circumstances? For some ideas, Creative Commons (CC), a non-profit organisation, offers a range of flexible copyright licenses for creative works You may even consider adopting one of CC’s licences if it suits your needs (see http://creativecommons.org/). As discussed above, however, there is no fixed format for a licence and a CC licence is only one of the ways to go about controlling your copyright work. b. It depends on the policy you adopt for your blog. If a reader leaves a comment, there is at least an implied licence that she allows her comment to be viewed on your blog. If you intend to use your readers’ comments beyond this, you should state so clearly on your blog. After all, original comments by readers belong to them, not you.
In general, the maker of a video owns the copyright to it. When a video-recording is posted onto a website, a copy is made. This involves the reproduction right of the copyright owner. Further, the communication right is involved as the video is made available on the Internet. Thus, if you want to post the video-recording onto websites like YouTube and you are not the maker of the video, you should get the consent of the copyright owner.Apart from copyright concerns, you may also want to consider Internet safety and personal privacy issues before posting the video-recording for the world at large to view.