TBH there are several routes, 1 is to use a seperate media player as in hardware as you can get a software based media player aswell.
The hardware version needs to support the movie file format to be able to watch these as in divx, mpeg4, mov, amongst many others, so you need to check the format of the movie files on her laptop 1st mate before buying a hardware media player as you might end up with a media player that wont play her films.
I would say your best bet is to plug straight into the TV assuming hdtv via cable from laptop tbh, I do this with mine given I have hdmi port on both.
Using this route all comes down to what connections your laptop & tv have mate, if her laptops has a pc output as in 15pin dsub connector on laptop & tv you could link the screen up & then run an audio output from laptop to the tv,hers may have a video out aswell, but if the laptop is fairly new it might have an hdmi port that carries the video & audio together in one cable, so when you play the film on the laptop it can if setup correctly in the laptop display preferances, will also play on the tv or solely on the tv, benefits of hdmi use is the higher image & sound quality, alot easier overall tbh.
Also using the laptop inconjunction with the tv instead of seperate media player would limit your risks of the movie file formats not working as laptop probably plays most of them with ease & easily get free software to play many formats, where as hardware based media players have a limited number it will play.
Which laptop does she have, make & model number would help us advise better.