I have done some research on getting BR4 beta screenshots after one day randomly finding some just by Google Search. I pretty much have found around 3-4 phases shown in both videos and screenshots: The first video (shown below) is probably the earliest public footage, and it shows early lifebars (with cyan for Human fill and red for Beast fill), the Hit Counter being gray, intros being similar to Primal Fury's, no names below the lifebars, and the logo looking a bit different, but there is no sound in this first video though. But it also shows the fact that the new beast gauge system was already implemented as a idea from early reveals. This trailer will be referred as the "first phase".

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The "second phase" can be seen from the first 3 screenshots in the slideshow above: Even though the lifebars frame are still the same, the Cyan/Red got changed to Blue/Yellow, which stuck until the near final phases of the game. The "third phase" could kind of be the second trailer video displayed below: Though we don't have footage of this supposed second phase, I assume the trailer is ahead from the second one because of the hit counter being yellow; and differences shown in the trailer is that the announcer and Jenny's voice clips are from Bloody Roar Extreme, the "Get Ready" label is noticeably different, intro cameras look like Extreme's and the music is also still a placeholder from Extreme/PF. The "last phase" of beta screenshots can be seen in the last 3 screenshots of the slideshow: The hit counter seems to be final and so was the lifebar frame, but the fills were still Blue/Yellow, the "FIGHT" font above the lifebars is different, and there still aren't names displayed.

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And yes, I may have just judged most shots because of solely the lifebar, but that and the few early videos we got are as far as we know atm about this game pre-release period; but it was already clear how the game was based off Primal Fury/Extreme's engine, something that's still clear in the final game.