The question if the tiger and crane form has been changed from the original form depends on who you believe. According to Sifu Wing Lam the form was created by Wong Fei Hung. I believe, but I am not sure about this, that this reflects the opinion of the Chiu Kao branch of Hung Gar. According to Lam Sai Fai, the son of Lam Jo and representative of the Lam family of Hung Gar, the tiger and carne form was created by the founder of the style Hung Hei Gung. According to the Lam family the form was re-choreographed by Wong Fei Hung. Now take your pick what you believe.
In any case the tiger and crane form we learn today was created by Wong Fei Hung with minor differences between the different Hung Gar branches.
That also answers the question if a video exist of the form before it was re-choreographed. No video exists. At that time the photo camera had been just invented.