Making a legal tube site in general is extremely difficult to do. The problem is that most international laws prohibit the distribution of copyrighted material. In the United States, the Digital Millennium Copyright Act (DMCA) explicitly prohibits the redistribution of electronic copyrighted material without prior consent from the copyright holders. Many adult tube sites attempted to avoid this by using a clause in the DMCA which does not allow for copyright holders to prosecute a transparent medium. However, what many people fail to realize is that the DMCA only prevents prosecution if the transparent medium's owner is unaware of the violation. Once made aware of the violation, they are required to remove the offending item. Failure to remove the item can result in prosecution. This is what got PornHub in trouble (and is also why many tube sites are moving to a paid [aka "premium"] structure). The truth is that it takes a lot of money, time, and experience to run an adult tube site. It also takes a lot of experience to run one that is profitable. If you are looking for tips on running a legal adult tube, here is what I would suggest:

1. Only allow for people to upload amateur content (amateur as in home-made and not production amateur). Amateur content does not fall into the copyright laws. Further, manually verify that your members are compliant. Many people will attempt to upload stuff that contains links, etc. For videos like that, delete them or do not approve them. People will complain, but in the end, it's your site and you can do whatever you want with it.

2. Provide the studios with a mechanism for uploading their own content. Further, work directly with the studios on putting their content online. Note, however, that most studios will not even talk to you unless your site is worth their time so be sure that your site is unique and has a lot of quality traffic before even approaching them.

3. Do not "swipe" videos. Swiping violates two copyrights. First, it violates the content owners copyright as they did not give you permission to host the video. Second, it violates the site that you swiped the video from as they did not give you permission to swipe it.

4. Any "house" content should be purchased by content distributors and should come with either broadcast or public viewing rights. This means that if you purchase content to go on your site, that content should not be for "private use" such as adult DVDs. Rather, it should come with distribution rights (so that you can show the video on your site).