Description:
Embedded videos have a thin black line around them that I am unable to remove.

Setting the line to "None" has no effect. I tried changing all of the boundary colors to white in Tools > LibreOffice > Application Colors, but this had no effect.

When using a black video with a slide that has a black background the line is no longer perceptible, so it appears to be a black line that is ~1 pixel wide.

While a cosmetic issue, it affects the presentation quality of all presentations that include high quality videos with light backgrounds that are meant to blend into the background.

Steps to Reproduce:
1.Produce an MP4 video with a white background, say with Manim (example provided in "Other Information")
2.Insert into a presentation with white background
3.Go to Tools > LibreOffice > Application Colors and change all boundary colors to white and apply
4.Start presentation

Actual Results:
Video plays with a thin white boundary line

Expected Results:
Video plays with no boundary line


Reproducible: Always


User Profile Reset: No

Additional Info:
``` python
# python class to produce an example Manim video w/ a white background
# throw this into a file 'scene.py'
# then run `manim -qh scene.py AnimatedSquareToCircle`
# file is saved to './media/videos/scene/1080p60/AnimatedSquareToCircle.mp4'
class AnimatedSquareToCircle(Scene):
    def construct(self):
        self.camera.background_color = WHITE
        circle = Circle()  # create a circle
        square = Square()  # create a square

        self.play(Create(square))  # show the square on screen
        self.play(square.animate.rotate(PI / 4))  # rotate the square
        self.play(
            ReplacementTransform(square, circle)
        )  # transform the square into a circle
        self.play(
            circle.animate.set_fill(PINK, opacity=0.5)
        )  # color the circle on screen
```

Help - About LibreOffice

Version: 7.6.2.1 (X86_64) / LibreOffice Community
Build ID: 56f7684011345957bbf33a7ee678afaf4d2ba333
CPU threads: 12; OS: Linux 6.5; UI render: default; VCL: gtk3
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