It says in the titles that's it's on the Yalu River, but in truth this actuality was shot in New Jersey and that River is probably the Passaic. The film companies had been offering battle footage since the Spanish-American and Boer Wars, always shot in New Jersey. Edwin S. Porter may have been a great and inventive director, but there was no way he was going to take a ship to the Far East for authentic battle footage, when his audience couldn't tell a Mauser rifle from a javelin. The war probably wouldn't last that much longer, anyway. Russia was sending a fleet to Japan, and if they hadn't surrendered before then, they would probably sink a couple of the islands in their fury.
As history tells us, when the Russian fleet got there, the Japanese sank them, triggering off mutinies and a move towards representative democracy.... squelched as soon as possible. It was the greatest naval upset since... 1898, when the modern American fleet entered Manilla Bay and discovered that many of Spain's vaunted battleships were older than Old Ironsides.
For those of you who don't want to bother looking at the film, it consists of the Japanese encampment, where the soldiers are exercising beneath their flag. The Russians attack, take the camp and then are driven off. No one seems to be shot. After all, this is a war between civilized nations.