使用for循环使用open（）无法下载文件？

Question

我想下载一些视频，然而，迭代链接并将它们传递到open()功能只会下载第一个视频，然后引发OSError。

以下是打印出的内容

Downloading 1-Video1
[Downloading] 100% |###########################################| Time: 
0:03:16
[1-Introduction] Successfully Downloaded
    with open(str(file_name) + '.mp4', "wb") as f:
OSError: [Errno 22] Invalid argument: "2-Video2.mp4"

以下是我的代码片段

# iterate over a dict containing k as the stage name and v as a list of
# all the videos in that stage
for k, v in stages.items():
    make_dir(k)
    os.chdir(k)
    for i in v:
    # i[0] is the title of the video, i[1] is the video link
        video_download(i[0], i[1])

def video_download(file_name, video_link):

    with open(file_name + '.mp4', "wb") as f:

        URL = requests.get(video_link)  # , auth=(EMAIL, PASSWORD)
        soup = BeautifulSoup(URL.text, 'lxml')

        video_mp4_link = soup.find('source', {'type': 'video/mp4'})['src']

        print('\n' + "Downloading %s" % file_name)

        response = requests.get(
            video_mp4_link, stream=True)
        total_length = response.headers.get('content-length')

       # check if there is a content lenght
        if total_length is None:
            f.write(response.content)
        else:
        # downloading the video with a progress bar
            dl = 0
            total_length = int(total_length)

            widgets = ['[Downloading] ', Percentage(), ' ',
                   Bar(marker='#', left='|', right='|'), ' ', ETA(), ' ']

            pbar = ProgressBar(widgets=widgets, maxval=100)
            pbar.start()

            for data in response.iter_content(chunk_size=8192):
                dl += len(data)
                f.write(data)
                pbar.update((dl / total_length) * 100)

            pbar.finish()
        print("[%s] Successfully Downloaded" % file_name)

# I am going to use it a lot that's why I created the following func
def make_dir(directory):
    try:
        os.makedirs(directory)
    except OSError as e:
        if e.errno != errno.EEXIST:
            raise