What do you think about the following changes?
`sub_id` -> `transcript_name`
`srt_subs ` -> `data`
```python
if lang == 'en':
    if self.sub:  # HTML5 case and (Youtube case for new style videos)
        transcript_name = self.sub
    elif self.youtube_id_1_0:  # old courses
        transcript_name = self.youtube_id_1_0
    else:
        log.debug("No subtitles for 'en' language")
        raise ValueError

    data = Transcript.asset(self.location, transcript_name, lang).data
    from_format = 'sjson'
else:
    data = Transcript.asset(self.location, None, None, self.transcripts[lang]).data
    transcript_name = os.path.splitext(self.transcripts[lang])[0]
    from_format = 'srt'

filename = '{}.{}'.format(transcript_name, transcript_format)
content = Transcript.convert(data, from_format, transcript_format)

```