I am trying to display a video using Gtk4 and Haskell but I’m having some trouble doing this.
Here is my code up so far. I have modified the example from https://github.com/haskell-gi/haskell-gi/blob/master/examples/Gtk4/gtk4-example.hs and I now have this.

{-# LANGUAGE OverloadedStrings, OverloadedLabels, ImplicitParams #-}

import Control.Monad (void)
import System.Environment (getArgs, getProgName)

import Data.Int (Int32)

import qualified GI.Gtk as Gtk
import Data.GI.Base

activate :: Gtk.Application -> IO ()
activate app = do

  --img1 <- Gtk.pictureNewForFilename (Just ("D:/stack-projects/gtk-intro-twelve/redbus"))
  --img3 <- "D:/stack-projects/gtk-intro-twelve/Glossaryck-4.png"
  --img2 <- Gtk.pictureGetFile img3
  --img <- Gtk.pictureSetFilename (Just "D:/stack-projects/gtk-intro-twelve/Glossaryck-4.png")

  video1 <- Gtk.pictureNewForPaintable (Just ("D:/stack-projects/gtk-intro-twelve/redbus.mp4"))

  -- #append box img1

  window <- new Gtk.ApplicationWindow [#application := app,
                                       #title := "Hello",
                                       #child := video1]
  #setDefaultSize window 1427 1080
  #show window

main :: IO ()
main = do
  app <- new Gtk.Application [#applicationId := "haskell-gi.Gtk4.test",
                              On #activate (activate ?self)]

  -- If the application does not need to parse command line arguments
  -- just pass Nothing.
  args <- getArgs
  progName <- getProgName
  void $ #run app (Just $ progName : args)

I have first tried to print an image on screen using img1 <- Gtk.pictureNewForFilename (Just ("D:/stack-projects/gtk-intro-twelve/Glossaryck-4.png")) and it worked.
I then tried doing the same with img1 <- Gtk.pictureNewForFilename (Just ("D:/stack-projects/gtk-intro-twelve/redbus.mp4")) to output the requested video but it didn’t work.

So then I tried with video1 <- Gtk.pictureNewForPaintable (Just ("D:/stack-projects/gtk-intro-twelve/redbus.mp4")) but it threw the error

D:stack-projectsgtk-intro-twelveappMain.hs:19:13: error: [GHC-10283]
    * Couldn't match representation of type `a0'
                               with that of `ManagedPtr ()'
        arising from a superclass required to satisfy `Coercible
                                                         a0 (ManagedPtr ())',
        arising from a superclass required to satisfy `ManagedPtrNewtype
                                                         a0',
        arising from a superclass required to satisfy `GObject a0',
        arising from a use of `Gtk.pictureNewForPaintable'
    * In a stmt of a 'do' block:
        video1 <- Gtk.pictureNewForPaintable
                    (Just ("D:/stack-projects/gtk-intro-twelve/redbus.mp4"))
      In the expression:
        do video1 <- Gtk.pictureNewForPaintable
                       (Just ("D:/stack-projects/gtk-intro-twelve/redbus.mp4"))
           window <- new
                       Gtk.ApplicationWindow
                       [#application := app, #title := "Hello", ....]
           #setDefaultSize window 1427 1080
           #show window
      In an equation for `activate':
          activate app
            = do video1 <- Gtk.pictureNewForPaintable
                             (Just ("D:/stack-projects/gtk-intro-twelve/redbus.mp4"))
                 window <- new Gtk.ApplicationWindow [#application := app, ....]
                 #setDefaultSize window 1427 1080
                 ....
   |
19 |   video1 <- Gtk.pictureNewForPaintable (Just ("D:/stack-projects/gtk-intro-twelve/redbus.mp4"))
   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^

Error: [S-7282]
       Stack failed to execute the build plan.

I don’t know what this means. I’m guessing it has something to do with GObject and the fact that I should somehow first turn the variable video1 into a GObject? But I’m not really sure. Could you point me in the right direction?