Finding resources online is not the challenge. Finding high-quality ones can be. Be picky! Know exactly where you are getting the video, photo, etc. While you will instinctively be using some filters like relevance to your need, currency, etc., I would suggest thinking a lot about the authority of the resource. Who wrote it or who is responsible for it? Why should you care what they think?
To find out who is responsible for the resource, look for an About Us link. If it's not at the top, or in the footer, then you may want to ignore them. If the website isn't obvious about who or what they are and why they exist, then they aren't even trying to be taken seriously. Try googling the name of the organization, to find out what others think of them.