You know what really pisses me off? Youtubers who shamelessly use other people's artwork in videos and thumbnails without the consent of the artist.
Seriously. Let's say you draw a really awesome piece of artwork. It took you several weeks to complete, but now it's finally done. You post it online and wait for someone else to find it and appreciate it, giving you the encouragement to continue to create art and grow as an artist.
But then you notice something. While looking around youtube, watching videos of your favorite TV show, movie, comic, or game your artwork is based on, you see a video with YOUR artwork as the thumbnail
Confused as to why you were un-aware that someone had used your artwork, you click on the video and watch it, looking for some form of credit to you since you are the one who drew the picture. Absolutely nothing. Not a single mention of you, or the source of your artwork.
You then look down in the comments. You see people praising the artwork in the thumbnail and complimenting the Youtuber for having such amazing artistic skills, even though he/she isn't the one who drew the picture.
Finally, you go back to the place where you posted your artwork. Even though the video that used your art has nearly a million views, you have received next to nothing in terms of appreciation for your hard work.
(So yeah, if any of you are youtubers or plan on becoming youtubers in the future, don't do this please. If you see something on google images that you like, please try finding the source of the picture and ask the artist if you can use it before you actually... Well... use it. If not, at least credit the artist in some way so they get the attention they deserve. This goes for really anyone producing content on the internet. I just see it on Youtube a lot nowadays)