I saw a QiGong beginners video on PBS the other night and thought it very fascinating. What would be good videos to get? Are there videos? Can it even be learned from a video or is it a waste of money?
You should begin, if at all possible, by taking intro classes with a teacher.
There are many videos and books out there, in bookstores and available on line. Experienced practitioners can gain a lot from these.
Would I say start learning by book or video? No - You will have many questions, and you cannot ask a video. A video cannot reach out and correct a serious mistake. Beginners also have difficulty picking out the right book or video.
For a teacher, I would first look at places where Tai Chi is taught. Though distinct and different arts, they are often taught and practiced together. There have been estimates of hundreds of different Qi Gong forms - the health, calming and exercise types are common, but there are some martial types and others which are Chinese medicinal. Again, an instructor can assist in choosing what's right for you.
every system of martial arts contains within it a 'Qi Gong' practice. depending on the martial style it will either (a) form the basic foundation upon which all else becomes built, or (b) the exact opposite, the high level stuff a student does not learn until proven worthy through years of loyal training.
some qigong has been culled out from the martial style, and offered up for those that are philosophically opposed to all things violent, kind of a 'chinese yoga'. i do not comment on this.
my suggestion is that since you ask the question on a 'martial arts' forum, that you (a) if you are already in a martial program to discuss with instructor or senior students, (b) determine why you'd like to practice a qigong (curiosity from a tv program is one thing, but qi gong will take an ongoing committed and dedicated practice to become meaningful)
once you understand 'why' qigong, then it may become easier for you to determine which style and which teacher is best for you. for example, if you are looking to bring balance into your life, tai chi qi gong is a good choice. if you are looking to cope with changes in your life, or possibly become a conduit for change, ba gua qi gong would be appropriate.
at that point, it gets a little tricky because good qi gong teachers do not grow on trees, and video/book learning is a dead end. just like any other personal relationship, a good teacher is one thing... but more important is whether that good teacher is good for you. you'll never know until you go and do.