I don't see flickering in Firefox 36 on Windows 7. The classic view definitely is using Flash (unlike the updated view).

The typical things you might try to Flash playback issues include disabling use of hardware acceleration by both Firefox and the Flash plugin:

In Firefox:

• "3-bar" menu button (or Firefox menu) > Preferences > Advanced > General mini-tab

Uncheck the box for "Use hardware acceleration when available"

This change takes effect the next time you quit Firefox and start it up again.

In Flash:

right-click some Flash media (or Mac equivalent of right click!) > Settings

Try the first of the little icons along the bottom of the dialog (looks like a very faded monitor) and uncheck the box for Enable hardware acceleration.

See this support article from Adobe for more information: http://helpx.adobe.com/flash-player/kb/video-playback-issues.html#main_Solve_video_playback_issues

Do either of those help?

Also, in case one of your extensions is involved, could you test the classic Street View in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any difference?