Please try the above techniques in the video first. Remember that some difficulty in removal is good because it keeps your Fi secure. However, if you find it is too difficult to remove the Fi unit from the adapter there is a way to "tune" the locking tab. Please read the entire paragraph before proceeding.

The locking tab is made of Nylon which has an interesting material property: it becomes more rubbery when coaxed into absorbing small amounts of water, and gets more stiff when dehydrated.  To soften the locking tab, submerge your adapter in hand-washing-warm water for about 5 seconds, then test it. Repeat if necessary. Please note that the adapter is designed to remain secure for regular aquatic activities such as swimming. However, because tap water can get much warmer than typical swimming water, warm tap water is potentially capable of making the tab too soft for security. If this happens, leave the adapter somewhere warm and dry (but do not heat!) - the tab will stiffen up again, though depending on environmental conditions it may take a few hours to some days.