main.py

import kivy

kivy.require('1.9.0')

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen, NoTransition
from kivy.properties import ObjectProperty
from kivy.uix.videoplayer import VideoPlayer
from kivy.uix.actionbar import ActionBar
from kivy.uix.button import Button

class ScreenTwo(Screen):
    def test_on_enter(self, vidname):
        #self.add_widget(Button(text="Back"))
        self.vid = VideoPlayer(source=vidname, state='play',
                               options={'allow_stretch':False,
                                        'eos': 'loop'})
        self.add_widget(self.vid)

    def on_leave(self):
        pass

    def onBackBtn(self):
        self.vid.state = 'stop'
        self.remove_widget(self.vid)
        self.manager.current = self.manager.list_of_prev_screens.pop()

class ScreenOne(Screen):
    def onNextScreen(self, btn, fileName):
        self.manager.list_of_prev_screens.append(btn.parent.name)
        self.manager.current = 'screen2'
        self.manager.screen_two.test_on_enter('Resources/Videos/' + fileName +'.mp4')

class Manager(ScreenManager):
    transition = NoTransition()
    screen_one = ObjectProperty(None)
    screen_two = ObjectProperty(None)
    screen_three = ObjectProperty(None)

    def __init__(self, *args, **kwargs):
        super(Manager, self).__init__(*args, **kwargs)
        # list to keep track of screens we were in
        self.list_of_prev_screens = []

class ScreensApp(App):
    def build(self):
        return Manager()

if __name__ == "__main__":
    ScreensApp().run()