Any way to add Blinking Text to a clip?

I was wondering if there is a way to add text to a clip that will keep changing colors at specific intervals (obviously I could manually split the clips up and apply the differently-colored filters to each clip in turn, but that’s not really viable for a longer project…)

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The answer to both questions are you could use the HTML Overlay filter and produce the effects using CSS animation or Javascript.
Use google to find out more.

Alternatively, a text overlay can be added as lengthier as the original video track itself and setup with base color preference. And then you can split this overlay and change colors wherever you want without any external code as such. If looking for some ideas, take a look at one of my tutorials on this topic.