Work with WebVTT files

Hi,

Will be possible to make it work with WebVTT Files? Something like this:

```
WEBVTT

00:00:00.000 --> 00:00:10.000
213509-35685.jpg#xywh=0,0,120,68

00:00:10.000 --> 00:00:20.000
213509-35685.jpg#xywh=120,0,120,68

00:00:20.000 --> 00:00:30.000
213509-35685.jpg#xywh=240,0,120,68

00:00:30.000 --> 00:00:40.000
213509-35685.jpg#xywh=360,0,120,68

00:00:40.000 --> 00:00:50.000
213509-35685.jpg#xywh=480,0,120,68

00:00:50.000 --> 00:01:00.000
213509-35685.jpg#xywh=600,0,120,68

00:01:00.000 --> 00:01:10.000
213509-35685.jpg#xywh=720,0,120,68

00:01:10.000 --> 00:01:20.000
213509-35685.jpg#xywh=840,0,120,68

00:01:20.000 --> 00:01:30.000
213509-35685.jpg#xywh=960,0,120,68

00:01:30.000 --> 00:01:40.000
213509-35685.jpg#xywh=1080,0,120,68

00:01:40.000 --> 00:01:50.000
213509-35685.jpg#xywh=0,68,120,68
```

Thanks!