I have long relied upon Flickr's advanced search[1] for this purpose. It allows a Creative Commons license constraint for commercial usage or use as source mate

I have long relied upon Flickr's advanced search[1] for this purpose. It allows a Creative Commons license constraint for commercial usage or use as source material. The advantage to their search is with the combined video search and finer media segmenting. [1] https://www.flickr.com/search/advanced/ https://www.flickr.com/search/advanced/