what about music/sound or even video; is it ok to use sound loops, short movieclips in flash/video files for non-commercial use?
In my opinion, it depends.
Is the sound clip you want to use some sort of press clip or the like, something that is intended to be distributed? i.e. did the author make it specifically available for you to use? Did the author include statements to that effect? If not, i.e. if it’s someone’s music, or a home video, I would say it’s safest not to use any of it without permission.
The commercial use aspect generally only comes into play in combination with other factors, such as attachment of criminal penalties or damages. Non-commercial use is not a defense to copyright infringement.
A few notes from the US Copyright Office:
https://www.copyright.gov/help/faq/faq-fairuse.html#howmuch
https://www.copyright.gov/help/faq/faq-fairuse.html#sued
https://www.copyright.gov/help/faq/faq-definitions.html#infringement
All in all, I would say think about how you would like to be treated. Would you feel the same way if someone else was using your hard work the same way on their website?
I think it’s really great that you are educating yourself about being respectful of copyright! ??