|If a video doesn't have a budget, it's usually not worth doing.|
Over the years, I have been approached and asked to do productions for free. In some of those situations I have agreed to do the production. I'm of the feeling that if it's for a good cause or will help a friend, I'm all in.
When a for-profit company asks for a freebie, that's totally different. I find it very inappropriate for a project manager, who is not donating his or her time, to ask a video professional to donate theirs. I have done portfolio work (non-paid) for friends, but I will no longer do so in a business relationship. Corporate clients usually lose a little respect for those who are willing to do freebies, not to mention it sets an expectation of low value in the craft. We as video professionals, have a responsibility to maintain the respect in our profession.
In any case when performing the duties of a video professional, you should never do a project if you feel that you are getting absolutely nothing out of it. When doing charity work, there is a feeling of using your skills to help the greater good. Generally when a company asks you to do work "on spec" with a promise of future work, always assume that future work will never come. Is the job still worth doing? The best jobs to do as freebies are the ones that you feel good about working on.
If you're looking for that next video project, the one that you're asked to do for free, will probably not be one you'll be proud enough of to include on your reel. Steer clear of those profit-making companies that ask for a valuable service without any offer of compensation.