Set video filters

Example

import { FfmpegClass } from "../mod.ts"

const ffmpeg = new FfmpegClass();

ffmpeg.videoFilters(
    {
      filterName: "drawtext",
      options: {
        text: "thingy",
        fontsize: "60",
        x: (856 / 2 - 30 * "thingy".length / 2),
        y: "H-240",
        fontcolor: "white",
        shadowcolor: "black",
        shadowx: "2",
        shadowy: "2",
      },
    },
);