当我搜索视频时，带有pytube的Python YouTube下载程序崩溃

Question

我正在用Python制作YouTube视频下载程序。我用PyQt进行了设计，并在空闲状态下编辑了代码。这是代码

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'YTD.ui'
#
# Created by: PyQt5 UI code generator 5.15.2
#
# WARNING: Any manual changes made to this file will be lost when pyuic5 is
# run again.  Do not edit this file unless you know what you are doing.


from PyQt5 import QtCore, QtGui, QtWidgets
from pytube import YouTube


class Ui_MainWindow(object):

    link = ''
    video = None
    
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(354, 210)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.plainTextEdit = QtWidgets.QPlainTextEdit(self.centralwidget)
        self.plainTextEdit.setGeometry(QtCore.QRect(10, 10, 261, 31))
        self.plainTextEdit.setStyleSheet("font: 12pt \"MS Shell Dlg 2\";")
        self.plainTextEdit.setPlainText("")
        self.plainTextEdit.setObjectName("plainTextEdit")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(270, 10, 71, 31))
        self.pushButton.setObjectName("pushButton")
        self.label = QtWidgets.QLabel(self.centralwidget)
        self.label.setGeometry(QtCore.QRect(20, 80, 51, 21))
        self.label.setObjectName("label")
        self.label_2 = QtWidgets.QLabel(self.centralwidget)
        self.label_2.setGeometry(QtCore.QRect(20, 99, 51, 21))
        self.label_2.setObjectName("label_2")
        self.label_3 = QtWidgets.QLabel(self.centralwidget)
        self.label_3.setGeometry(QtCore.QRect(20, 120, 51, 21))
        self.label_3.setObjectName("label_3")
        self.label_4 = QtWidgets.QLabel(self.centralwidget)
        self.label_4.setGeometry(QtCore.QRect(20, 140, 51, 21))
        self.label_4.setObjectName("label_4")
        self.label_5 = QtWidgets.QLabel(self.centralwidget)
        self.label_5.setGeometry(QtCore.QRect(80, 80, 251, 21))
        self.label_5.setText("")
        self.label_5.setObjectName("label_5")
        self.label_6 = QtWidgets.QLabel(self.centralwidget)
        self.label_6.setGeometry(QtCore.QRect(80, 100, 251, 21))
        self.label_6.setText("")
        self.label_6.setObjectName("label_6")
        self.label_7 = QtWidgets.QLabel(self.centralwidget)
        self.label_7.setGeometry(QtCore.QRect(80, 120, 251, 21))
        self.label_7.setText("")
        self.label_7.setObjectName("label_7")
        self.label_8 = QtWidgets.QLabel(self.centralwidget)
        self.label_8.setGeometry(QtCore.QRect(80, 140, 251, 21))
        self.label_8.setText("")
        self.label_8.setObjectName("label_8")
        self.pushButton_2 = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton_2.setGeometry(QtCore.QRect(270, 160, 75, 23))
        self.pushButton_2.setObjectName("pushButton_2")
        MainWindow.setCentralWidget(self.centralwidget)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)
        self.pushButton.clicked.connect(self.on_search_clicked)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "SEARCH"))
        self.label.setText(_translate("MainWindow", "Title:"))
        self.label_2.setText(_translate("MainWindow", "Author:"))
        self.label_3.setText(_translate("MainWindow", "Views:"))
        self.label_4.setText(_translate("MainWindow", "Likes:"))
        self.pushButton_2.setText(_translate("MainWindow", "Download"))

    #THIS IS THE METHOD THAT I WROTE MYSELF
    def on_search_clicked(self):
        global link
        link = self.plainTextEdit.toPlainText()
        global video
        video = YouTube(link)
        self.label_5.setText(video.title)
        self.label_6.setText(video.author)
        self.label_7.setText(str(video.views))
        self.label_8.setText(str(video.likes))

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

问题是，当我在plainTextEdit框中提供链接并按下pushButton时，应用程序崩溃。在on_search_clicked()中肯定有一些问题，因为它是我编写的唯一方法，其余的是自动生成的