I have a patent that describes an action that contain a use of digital photograph. There is a company is coping my patent except for the fact she uses live video instead of photos. I can easily prove that video is a sequence of photos because technically video is like many photos.. but the question is- from legal point of view- can I say that video is like many photos?
They are not legal terms per se. Even though law will accept the technical relationship between photograph and video, yet should concede that they are different because they are considered so in relevant technology field.
In patent prosecution, it may be considered whether claims based on video will be obvious to a person skilled in the art in the light of photograph based claims and description supporting the photograph based claims. This consideration may not have initiation at all when 'live video' based claims are taken into consideration. Because, very clearly, the same was not obvious to Nona (even possible application to video was also non-obvious to her) herself nor to anyone else (assuming absence of prior art).
For patent grant requirement is
35 U.S.C. 101 Inventions patentable
Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof may obtain a patent therefor, subject to the conditions and requirements of this title.  (After considerations under 35 USC 102 and 103 also).
IMO, the point here is she is using "live video instead of photos" which, for patent purpose, can be considered as new and useful improvement if not out and out "novel" and hence a suitable candidate for grant of patent and infringement prosecution/suit may not stand.
That's where a good patent attorney is helpful who can not only dig into what you have invented but also take care of fall outs of your invention which should be plugged.
Disclaimer : It is just personal opinion and not legal opinion or advice.