Yes there are several things you need to do. First of all find out who wrote the music and lyrics of any songs you intend to record. If the authors are the bands themselves, then obviously they can give permission or a suitable fee can be arranged as part of the overall deal. If they are covering songs by other people, you (and they) need a licence to do this. In most cases the collecting society PRSforMusic
can help here.
As for the actual recording of the performance, all the band members* need to sign an agreement allowing you to exploit their performance right. They also have something called "rental rights" but that would not appear to apply here. There are two separate forms avaialable on line: here
. Study the notes and see which best suits your arrangement. Of course you may be able to find other examples online.
Once you have both the copyright holder's permission or licence (for words and music), and the performers' agreement in place, copyright in the actual recording you make will be yours. If at some later stage your podcasts are pirated and appear on Youtube without your permission, you are the only person who can take action over the infringement. Obviously if other people attending the festival make videos on their phones etc, that is not your concern, and it would be up to the band to take action if this was thought necessary. In many instances bands see this as useful publicity and as they do not lose money by it, are happy to allow it.
You will need to get permission from the event organisers or promoters to film on the site. This is purely to do with the conditions of entry and nothing to do with intellectual property rights. This shouldn't be a major problem if the bands have already consented to the filming. It is possible that they may ask you to get public liability insurance if you will working in the audience area, but if you are only using a handheld camera without a tripod or extra lights, or are working in an area away from the public, this should not be necessary.
Just one final point. If the festival is held in England or Wales the forms I have linked to above will be OK. If the festival is held in Scotland then the law on copyright and performance right is the same, but you may need to check that any agreements you use conform to Scottish law.
There's a useful general checklist here
*if a band has a contracted manager, he may be authorised to sign agreements on behalf of all band members.