Copyright-Free Videos/audios how to Find on YouTube? | From Where will get Copyright-free videos?

For YouTubers, the Copyright strike is a big headache.  Here I am gonna show you where you can find copyright strike-free videos and audios, which you can use on your YouTube legally. One more way if you trimmed any of the youtube video and audio for 15 seconds or less than 15 seconds, a copyright strike will not come to you.  I usually do this for my youtube channel.