Oh hey something in my wheelhouse.

Was it a camera-related problem?

A little bit yes due to operator error, but mostly no; it's a modernization issue. Firstly we need a little bit of context about how film cameras work.

A strip of light-sensitive squares of film are pulled in front of a glass lens pointed at whatever the cameraman would like to capture. Now, you can't just drag these all in a row in front of the lens or it would just come out as a blur. The film cell needs to be moved into place covered, uncovered long enough to expose to light and imprint an image, then covered again. To accomplish this, a rotating shutter is synced up with the mechanism that moves the film strip so that it covers and uncovers the lens at the appropriate times. If you're having trouble visualizing here's an example. Obviously a little more modern than the cameras we'll be discussing here but the concepts are the same. Projectors work in fundamentally the same way but in reverse. A frame of film is pulled into place while a rotating shutter hides the motion, and, opposite of a camera capturing light from the outside, a light inside the projector shines onto the film strip outward. Whenever one of these images is shown, we call that a frame.

Modern film (not digital) movies are shot and projected at 24 frames per second. This has been the standard since the advent of sound with The Jazz Singer in 1927, but before that, cameramen could play it a little more fast and loose with the speed of the film. Though there are earlier examples of a basic camera/projector, such as a magic lantern, the first major examples we might recognize as a functional movie camera would be Edison's kinetoscope and the Lumière brothers' cinématographe which followed shortly after.

A major difference between these two systems was the rate at which they recorded and projected. The kinetoscope was run by a motor that was set to record at 46 frames per second whereas the cinématographe was run by a hand crank. It was designed to be spun at two turns per second, resulting in 16 frames per second filmed/projected. However this accuracy depended on the skill of the cameraman, or could even be intentionally spun faster and slower to create a sped-up or slowed-down effect. While this is not the primary reason that old films look fast it can account for changes in speed during play.

Ultimately, the Lumières' system became the standard which new cameras were modeled after for a number of reasons; namely portability and weight, the difference in volume between a hand crank and a motor, and the savings of using less film with a lower fps rate. As a result, silent films tend to be around 16 frames per second; a 2:3 ratio to a modern 24 fps film projector. Essentially, you're running one second of silent film through the projector in .66 seconds of real-time. If we had settled on Edison's design of more frames, silent films would look slower. A short clip of a kinetoscope film can be seen here for example.

Hope this helped, let me know if you have any questions.