while (my @section = splice @vidids, 0, 50) {
    my $idees = join ',', @section;
    my $uri = "https://www.googleapis.com/youtube/v3/videos"
           . "?part=items(viewCount)&id=$idees&key=$API_KEY";
    my $result = get($uri);
    my $json = decode_json($result);
    push @counts, map $_->{viewCount}, @{ $json->{items} };
}
[download]

Update: If you don't want to destroy the array, you can use an index:

while ($from <= $#vidids) {
    my @section = @vidids[ $from .. $to ];
    my $idees = join ',', @section;
    my $uri = "https://www.googleapis.com/youtube/v3/videos"
           . "?part=items(viewCount)&id=$idees&key=$API_KEY";
    my $result = get($uri);
    my $json = decode_json($result);
    push @counts, map $_->{viewCount}, @{ $json->{items} };

} continue {
    $from += 50;
    $to = $from + 50;
    $to = $#vidids if $to > $#vidids;
}
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($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]