Generally when it comes to making movie clips and trying to figure out what is spam and what is not, you kinda have to look at it from both sides. What is seen as spam and what is not can vary greatly depending on the situation.
Let's say if a user tends to post 5+ clips in a row, and continues to do so over and over again even though you are in a populated area where the chat is moving quiet fast. That surely could be seen as spamming and action could be taken on the user.
If you are in the corner of the map and the chat isn't hardly moving, and let's say every few 30 seconds or so a user is posting their movie clips. To you, this could be seen as spamming as your chat could not be moving very fast at all, when really it's technically not enough to be labeled as spam.
Really when it comes to trying to find a happy medium in movie clips and trying not to spam, try to consider posting just one clip every couple minutes or so. This helps to not clutter up a fast moving chat, as well as lighten the amount of clips other users will receive in a slower moving chat.