The error message you get is unhelpful because $! is not set by SDL::Video, nor is it documented to do so. The SDL::Video documentation on set_video_mode tells you to retrieve the error message using SDL::get_error.

#!/usr/bin/perl

use strict;
use warnings;
use SDL;
use SDL::Video;
use SDL::Surface;
use SDL::Rect;

my $screen_width  = 800;
my $screen_height = 600;

SDL::init(SDL_INIT_VIDEO);

my $screen_surface = SDL::Video::set_video_mode(
$screen_width, $screen_height, 32, SDL_ANYFORMAT);

my $mapped_color = SDL::Video::map_RGB(
   $screen_surface->format(), 0, 0, 255);
   
SDL::Video::fill_rect($screen_surface,
   SDL::Rect->new(
   $screen_width / 4, $screen_height / 4,   
   $screen_width / 2, $screen_height / 2),
   $mapped_color);
   
SDL::Video::update_rect(
   $screen_surface, 0, 0, 
   $screen_width,
   $screen_height);
   
sleep(5);

SDL::quit();
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I think I may be making progress. That example you gave is what I was using. After running your CPAN install script (woowee that is a lot of stuff) I had an issue running your Build.PL script.

Gonna use 'My::Builder::Unix' class ...
Require 'My::Builder::Unix' failed: Can't locate My/Builder/Unix.pm in
+ @INC
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Assuming I should've used the My/Builder/* files in the Alien::SDL package, I copied them over, but got another error

Can't locate object method "find_subsystems" via package "My::Builder:
+:Unix" at Build.PL line 526.
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Where and what version is the My::Builder::Unix class in your Build script coming from?

Using the Build.PL that comes with SDL Perl, the Build test gives these results.

root@sw:~/sdl/SDL_Perl-v2.2.6# ./Build test
t/apppm.t .......... ok   
t/cdrompm.t ........ ok   
t/colorpm.t ........ ok     
t/cursorpm.t ....... ok   
t/eventpm.t ........ ok   
t/fontpm.t ......... ok   
t/manifest.t ....... skipped: Author tests not required for installati
+on
t/mixerpm.t ........ ok   
t/mpegpm.t ......... skipped: smpeg support not compiled
t/musicpm.t ........ ok   
t/opengl.t ......... ok   
t/palettepm.t ...... ok   
t/rectpm.t ......... ok     
t/sdlgamerect.t .... ok     
t/sdlpm.t .......... ok   
t/soundpm.t ........ ok   
t/surfaceML.t ...... skipped: Author tests not required for installati
+on
t/surfacepm.t ...... ok   
t/timerpm.t ........ ok   
t/toolfontpm.t ..... ok   
t/toolgraphicpm.t .. skipped: SDL_gfx support not compiled
t/ttfontpm.t ....... ok   
t/videopm.t ........ skipped: smpeg support not compiled
All tests successful.
Files=23, Tests=184,  2 wallclock secs ( 0.12 usr  0.25 sys +  1.03 cu
+sr  0.50 csys =  1.90 CPU)
Result: PASS
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The t/videopm.t being skipped seems like something to be concerned about. I thought I saw smpeg being installed as a dependency in that CPAN script?

Currently, when I run the SDL test script, I get this.

Use of inherited AUTOLOAD for non-method SDL::init() is deprecated at 
+./test.pl line 14.
Can't locate auto/SDL/init.al in @INC
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I changed that part of the code to SDL->init() and got this  Can't locate auto/SDL/init.al in @INC Is it safe to assume that that init() sub should get installed when t/videopm.t isn't 'skipped'?

Try to add this first:

SDL::init(SDL_INIT_VIDEO);
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