Pieces of the texture disappearing as you walk.

[sand dome]

Example in the video:

[silver dust]

Looks like it may be an issue with some translucent textures/alpha values

[dusky girder]

Maybe you've incorrectly set the cull face? Some mods like sodium use this value to hide some parts of the models to increase performance.

How are you spawning the model?

[sand dome]

ItemsAdder

Actually, I use sodium.

However, I have some other models that don't glitch.