It is basically impossible that this is Pius X. He died in 1914, around ten years before the microphone/electrical recording was invented. Also, movie cameras could not record sound until the late 1920s. It required somebody going into a very small recording studio and speaking into a funnel to make a record. So unless this is old footage with a studio recording artificially imposed into it (which it doesn’t sound like, given that there is crowd noise in the background), it was not recorded until the late 20s or beyond.
Therefore, I am 99.9% certain that this is not Pius X, but instead Pius XI, who did live in the era of microphones and such technology.