capgetdriverdescription未声明？？！！
程序如下，VFW.PAS已经添加

unit VideoCapDrivers;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

type
TForm1 = class(TForm)
ComboBox1: TComboBox;
Label1: TLabel;
Label2: TLabel;
StaticText1: TStaticText;
Label3: TLabel;
StaticText2: TStaticText;
Label4: TLabel;
StaticText3: TStaticText;
procedure FormCreate(Sender: TObject);

private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);

var
wDriverIndex : DWORD;
DrvCount : Integer;
DrvName : array[0..80] of char;
DrvVer : array[0..80] of char;

begin
DrvCount:=0;
for wDriverIndex:=0 to 9 do
if capGetDriverDescription(
wDriverIndex,
DrvName,sizeof(Drvname),
DrvVer,sizeof(DrvName))then
begin
inc(DrvCount);
end;
StaticText3.Caption:=inttostr(DrvCount);
end;

end.

错误报告：
[Error] VideoCapDrivers.pas(43): Undeclared identifier: 'capGetDriverDescription'

请问怎么会有这样的错误呢？如何解决？
[解决办法]
var
Form1: TForm1;

implementation
uses vfw;

{$R *.dfm}

注：在此处添加 uses vfw;
虽然你工程中添加了vfw.pas，但你在此单元中未引用vfw.pas,所以未能解capGetDriverDescription函数
[解决办法]
对呀，最好没忘记引用相关的“单元”