Contract law is a funny thing and generally only comes into focus at times of dispute - been there.
Having been paid to shoot a video, unless you specifically agreed to retain copyright of the footage, law of precedence would indicate the footage belongs to the Client.
This being the case you certainly couldn't issue the footage to a third party without the Clients permission. If The Client has authorised use of the footage by an artist it isn't unreasonable for you to charge for your time and materials in facilitating the artists use. If the footage requires re editing you can charge for that as well.
Video is unlike photography in that, in most cases, the finished product is the result of many peoples work. Thus it is almost impossible to conclude who has intellectual rights over the finished product. It is no different to building a house. A brick layer doesn't get royalties on the sale of every house he has been involved in even though it was his graft which made it so. Neither does the Architect, even though it was his vision which brought the house into being. Video is the same. The owner is the person who paid for it.......unless, as noted eloquently above, the original artist/sport/venue confirm they are allowing the recording of their work under licence. In this case they are contributing to the video by discounting the cost in the provision of the spectacle.
If, however, you made it known that you were "investing" unpaid time in the project you were, in effect, contributing to paying for the project with your time that gives you a stake in the ownership.