Valera/fix start time end time 2

**Description**

This PR fixes:

- [YouTube] Total time in VCR timer is correct. Before it was 00:00:00 until the user clicked **Play**.

This PR adds:

- [YouTube, HTML5] Start-end time range is always shown, even before the user clicks **Play**.

**Original JIRA issue**

[BLD-529](https://edx-wiki.atlassian.net/browse/BLD-529)

Please note. BLD-529 has additional requirements that will not make it into this PR. They will be part of a separate PR. Discussed with @Lyla-Fischer .

**Reviewers**
- @polesye 
- @singingwolfboy