If you are interested in entering a festival or have entered your film in a festival, it is recommended that you first check the regulations to see at what point you can upload your short. Some festivals seeking premieres want to be the first medium by which the film is displayed. Others however will have no problem with you displaying the film initially online, so long as that particular film festival is the first of its kind to show the premiere of the film.
Short Film Online Rights are extremely important. In order to sell or license the rights of the short film to an online provider, or allow the film to be streamed, you first need to have all rights to the film. Should you choose to sell your rights, check to see if you will be giving the provider exclusive rights to the film. Basically this means that only the provider will be permitted to display your short. Always negotiate for non-exclusive rights so that you can still retain some rights to your film.
