import sys
from PyQt5.QtWidgets import QApplication, QWidget, QPushButton, QLabel
from PyQt5.QtGui import QMovie
def btn_click():
gif1 = QMovie("gif2.gif")
label_gif.setMovie(gif1)
gif1.start()
app = QApplication(sys.argv)
w = QWidget()
btn = QPushButton("Кнопка", w)
btn.clicked.connect(btn_click)
label_gif = QLabel(w)
gif = QMovie("gif1.gif")
label_gif.setMovie(gif)
gif.start()
label_gif.move(30, 30)
w.resize(500, 500)
w.move(500, 300)
btn.move(0, 0)
w.show()
sys.exit(app.exec_())