Thank you jya_ from #mythtv-users (irc.freenode.net) for identifying the location to change the skip time for playback using mythtv.
By default, mythtv skips 30 seconds FORWARD using the Right Arrow Key (->) symbol, and skips 5 seconds BACK using the Left (< - ) symbol on the keyboard. I wanted to change the skip back time to 15 seconds instead of 5...but where did they hide the setting? The adjustment is in mythfrontend. Navigate to the settings from mythfrontend: Setup -> Video -> Playback Groups -> Default
Your screen looks like:
Or whatever works for you. Thanks jya_.