VideoPress: picking poster from video frame causes the video to start playing from that frame

### Impacted plugin

Jetpack

### Quick summary

VideoPress has the option to set poster image using the option "Pick from video frame". However, this results in the video playing from that frame instead of from the beginning.

This issue was reproducible only on the Simple site.

### Steps to reproduce

1. Upload a video using VideoPress block
2. Set a poster image using a frame from the video.
3. Save the changes.
4. Visit the published page.
5. You will notice the frame you set as poster image.
6. Click on the video to play. You will notice that video will start playing from that frame instead of from the beginning.

Screen recording:

https://github.com/user-attachments/assets/812a4454-8514-4beb-8da1-62a22bea55b8

### Site owner impact

More than 60% of the total website/platform users

### Severity

Minor

### What other impact(s) does this issue have?

_No response_

### If a workaround is available, please outline it here.

User can upload a custom poster image to work around this bug.

### Platform (Simple and/or Atomic)

Simple

Start by reproducing the issue on a Simple site with the VideoPress block, following the listed steps and checking the published page. Trace how the selected video frame is applied as the poster and how playback is initialized; done means selecting a frame still shows that poster while playback starts from the beginning.

Written by the indexing model from the issue text.