Hi DS,
Since you didn't mention it I'll assume that none of the songs featured in the video were written by any of the band members.
Therefore we are talking about something called
performer's rights - sometimes called neighbouring rights - which are basically the right of a performer to decide whether his/her performance may be recorded (the reproduction right), and how the recording may subsequently be exploited. The forms of exploitation include making copies of the recording, selling, hiring out or lending those copies to the public, broadcasting the recording or making it available to the public. The last one would cover the situation where the video has been put on Youtube (which is not technically a 'broadcast'). You and your fellow band members need to have consented over the reproduction right before the recording was made, as it sounds as if you did, and although the other rights can be decided later on, it is better to agree them beforehand. Other than the reproduction right, the rights mentioned so far are property rights which you can transfer to other people by gift, sale or licence. It follow therefore that the property rights of the deceased band member may have passed to his heirs or could have been transferred to the remaining band members if this had been his wish.
Additionally, there are some moral rights, for instance that you are entitled to be credited as the artists* in the performance as long as you assert this right, and the right not to have your performance treated in a derogatory way. These rights cannot be transferred other than through a will or similar testamentary disposition, but they can be waived.
The person who made the recording (it doesn't matter if it was video, film or just a sound recording) is known as the producer and he owns the rights in the actual recording, but you the performers are entitled to fair remuneration from any financial gain he makes. In both cases the right exists for 50 years from the end of the year in which, either the performance took place (for all of your performer's rights) or the date that the recording is first released to the public in the case of the recording. Your entitlement to fair remuneration is known as your economic rights. These cannot be signed away to a third party other than a copyright collecting society (such as
PRSfor Music), and in the case where someone dies, their economic right passes to their heirs. It does not devolve to the remaining band members. The amount of the royalties payable should ideally have been agreed before the recording was made, but if there is any dispute about how much is 'fair', the Copyright Tribunal can arbitrate. However it sounds as if your relationship with the producer of the video is an amicable one, so hopefully that is not an issue.
Neither your rights nor those of the producer of the video are in any way affected by posting the video on YouTube. If someone takes a copy of video from Youtube and posts it elsewhere, or tries to sell copies of it, then you are both legally entitled to take action to stop this, although the person most directly affected is the producer of the recording. In the case where someone has unauthorised copies which they are trying to sell, this could well be a criminal matter, and you can ask Trading Standards to get involved in going after the perpetrators.
Where the reproduction and property rights are concerned these are held jointly by the band members (or their heirs). So for instance you would all need to agree to the broadcasting of the video. But the non-property rights are individual rights so any one of you may individually take legal action against other people in respect of those particular rights.
Dealing with all this rights is a complicated business, and if you and the band are intending to go professional or take things further in a semi-professional way you may need to read up on the subject in more detail. There as a number of websites which are worth checking out:
Bemuso
Music Law Advice
Music Law Updates
* a credit can be in your own names, a stage name or under the name of the band.