youtube parser v5

#!/usr/bin/python
print "Content-type: text/html\n\n"
# -*- coding:Utf-8 -*-
import urllib2


def check_channel_update(new_data, channel):
    fichier = open('video.txt', 'r')
    data = fichier.read()
    fichier.close()
    base_url = 'http://www.youtube.com'
    data = data.split('\n\n')[:-1] #do not forget to add delimiter at end of each channel !
    channel_old_data = ''

    for element in data:
        if channel in element:
            channel_old_data = data.pop(data.index(element))
            break

    if not channel_old_data : return False

    channel_new_data = ''
    for new_video in new_data:
        if not new_video in channel_old_data:
            print 'new video avalaible'
            channel_new_data += base_url+new_video+' '+title[new_data.index(new_video)]+'\n'
        else:
            break #leave loop cause no new video after that

    if len(channel_new_data):
        before, after = channel_old_data.split('\n',1)
        update =  before +'\n'+ channel_new_data + after
        data.insert(0, update)
        data = '\n\n'.join(data)
        data += '\n\n'

        write_data(data)

def write_data(data):
    fichier = open('video.txt', 'w')
    fichier.write(data)
    fichier.close()

def parse_html_source(url):
    data=urllib2.urlopen(url)
    data = data.read()

    start_tag = '<h3 class="yt-lockup-title">'
    data = [item.split('</h3>')[0] for item in data.split(start_tag)[1:]]
    title = [item.split('title="')[1].split('"  aria-describedby')[0] for item in data]
    link = [item.split('href="')[1].split('">')[0] for item in data]

    return title, link


def update_channel_file(): #used often
    fichier = open('channel.txt', 'r')
    data  = fichier.readlines()
    fichier.close()

    name_channel_update = data.pop(0)
    data.append(name_channel_update)

    fichier = open('channel.txt', 'w')
    [fichier.write(item) for item in data]
    fichier.close()
    print name_channel_update
    return name_channel_update.split(' ',1)[0]


url_channel = update_channel_file()

title, link = parse_html_source(url_channel)
check_channel_update(link, url_channel)