[Blinkx] Return could be improved to be more future proof

[abayet]

Checklist

• I'm reporting a site feature request
• I've verified that I'm running youtube-dl version 2021.04.26
• I've searched the bugtracker for similar site feature requests including closed ones

Description

In the blinkx.py extractor, the returned dictionary as it is generated in the _real_extract() function would make the execution crash if the layout of the source data changed for optional fields. There it is a screenshot of the problematic portion of code.

The optional fields "uploader" (line 81) and "timestamp" (line 82) are concerned. As mentioned in the youtube-dl coding conventions, it would more robust to use the method get().