Are you sure there's nothing in writing that you've signed or that your agent signed on your behalf that calls this a "work for hire"? You refer to the "initial work for hire," but if you haven't signed a contract stating that this video is a work for hire and therefore owned by the company, then YOU own the copyright to it, and they can't create any derivative work out of your final recording without your consent.
They presumably have the right to own and display your final video recording as a result of your oral contract and contract implied in fact by your and your agent's emails, but unless your raw footage was mentioned in these emails, they're not entitled to that. And even if they were, as mentioned, as long as you're the copyright owner, they can't alter your work to create a new version of it.
See an IP lawyer about registering the copyright to protect it from infringement, and do this ASAP given this dispute.
PLEASE READ THIS BEFORE YOU COMMENT, EMAIL ME OR PHONE ME. I'm only licensed in CA. This answer doesn't make me your lawyer, and neither do follow-up comments and/or emails and/or phone calls, and you shouldn't expect me to respond to your further questions if you haven't hired me. We need an actual agreement confirmed in writing before any attorney-client relationship is formed. This answer doesn't constitute legal advice, and shouldn't be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue.
I agree with the advice of my colleague. But be careful here. A contract can be formed by e-mails, text messages and other dealings among the parties. My guess is that the company and/or the agency believed that this was a "work for hire" project, in which event the company would be entitled to your raw footage.
Let's be practical here--even if you can claim to own the copyright in the raw footage, do you really want to require them to pay for it in this situation. You said that you "made a video for cheap to get future work." If your purpose is to get future work from this company or other companies, then you may be shooting yourself in the foot if you refuse to cooperate with them. Your reputation is very important, and if you fight with this company about this issue, the ramifications can be quite harmful to your reputation---particularly because most companies in situations such as this insist on proceeding on a work for hire basis. I would think very carefully about your long term objectives before asserting that you own copyrights in this footage---even if you are technically right you may be hurting your long term interests by fighting the company on this.
It's true that unless you were an "employee" -- and it sounds like you were an "independent contractor" instead -- your work for the company would not be a "work made for hire" unless "the parties have expressly agreed [to this arrangement] in a written instrument signed by them." (http://www.copyright.gov/title17/92chap2.html#201). However, as Attorney Ross points out, a "written instrument" can take many forms, including e-mails.
Furthermore, it is possible that you put something in an e-mail or other informal writing that "assigned" your intellectual property rights in the footage to the company. "Legalese" is not required to effect an assignment; "plain language," if it evidences the necessary intent, can result in transfer of rights as well. Again, some sort of written instrument is required, though the bar is quite low: a written confirmation of an oral transfer is sufficient (http://www.copyright.gov/title17/92chap2.html#204). (The appellate courts currently disagree over whether such a confirmation must be executed before the work is created, or is valid even after the work is created, if it confirms a pre-creation oral transfer.)
Going beyond the "work made for hire" doctrine and the rules about copyright assignments, there are a variety of legal tools that the company may be able to use to its advantage. (Some of them may work to your advantage, too, depending on the precise facts and your goals. But as my colleagues point out, one must keep in mind the potential *business* fallout from aggressive legal maneuvering.) I ran through the gamut of rights-transferring mechanisms on my blog at the following URL: http://lawoffashion.com/blog/story/04/20/2011/50 -- hopefully you will find it helpful.
This answer does not constitute legal advice, and should not be relied on in place of a consultation with an attorney. No attorney-client, contractual, or fiduciary relationship has been formed as a result of this post or anyone's use of it. The only manner in which an attorney-client relationship can be formed with Charles Colman Law, PLLC, is via a countersigned letter of engagement on CCL letterhead. Charles Colman is only admitted to practice law in New York State, and before New York federal district courts. Although he endeavors to answer all Avvo questions knowledgeably, he cannot and does not provide any guarantees as to the thoroughness or accuracy of his responses.