There is no strict rule when it comes to festival applications, however some major film festivals may have strict rules about world or US premieres which you must adhere to.
If you have a short film we recommend you submit it to a host of festivals nationally which will allow you to be able to travel physically to them and promote them. It’s easy to submit around the world, but often there is no funding in place to help you make the trip. In order to support your film, try to apply to festivals that are in line with the subject and genre of your story.
For music videos and shorts, there are a number of specialized festivals in American like the Chicago Film Festival or Hollywood shorts, that accept different kinds of categories. Make sure that you check the fine print when it comes to submitting, if you have had your film featured elsewhere. Some festivals do like to have the first screening.
Lastly, if you are going to put your film online, we recommend you wait until after the festival run to show it, or once it has been distributed on TV. If you are not interested in distribution for your short, putting it online after your film festival tour is fine.