Okay I ran into an issue somewhere but at this moment it is totally unknown what is causing it.
I purchased the diodes from RadioShack today, and placed it in the correct spot in the circuit and the "hobby motor" was rotating fine, both left and right, and the temp on the FETs were still doing fine as well.
Later I hooked up my linear actuator, it was working decent for the first run through test, however, I did notice that on my variable power supply, as the left and right switching was occurring, the power supply had a slight short circuit effect happen to it. It didn't completely cut out the entire circuit's power, but there was a noticeable power loss for a split second as it was switching directions or polarities I should say.
So afterwards I decided to swap the photo-transistors with the clear photo-transistors which are more sensitive to light than the tanned one's you see in the first video. So after using those for a few seconds, again the circuit worked fine, really, the circuit worked "better" with the clear photo-transistors.
Anyway, soon I noticed I couldn't get the linear actuator to pull in it's stroke, it would only push out the stroke, or in other words, only 1 polarity would work. I then notice something smoking, which was my Q4 FET, and that was the only one to appear as to getting extremely hot whenever I shined the light source to the photo-transistor that activates that side of the H-Bridge (Q1 & Q4).
So I tried re-checking my wiring, swapping the diode, as well as both FETs (Q1 & Q4), but still only 1 polarity works. So I'm still puzzled at the moment what exactly went wrong here, but as I stated before, while using the linear actuator you can really notice the polaritiy switch from the minor short circuit that seems to occur, something that I believe I didn't notice using the hobby motor. I'll have to run more test tomorrow though as it's getting late. Let me know if you guys think you know what exactly may be causing this issue or what I should re-check based on the info I gave, or if you need more info let me know.